15 A Psalm of David.
1 O I AM, who shall sojourn in your tent? / Who shall dwell on your holy hill? / 2 He who walks blamelessly and does what is right / and speaks truth in his heart; / 3 who does not slander with his tongue / and does no evil to his neighbor, /nor takes up a reproach against his friend; / 4 in whose eyes a vile person is despised, / but who honors those who fear the Lord; / who swears to his own hurt and does not change; / 5 who does not put out his money at interest / and does not take a bribe against the innocent. / He who does these things shall never be moved.
A man stranded alone for many years was finally rescued when a passing plane saw his “SOS” marked on the beach of what was thought to be an uninhabited island. When a rescue party arrived, he proudly showed off the structures he built over the years to make the island more habitable. He showed them his living quarters, his storage building, and his cookshack. He even showed them the chapel he built to worship God on Sunday mornings. His rescuers were impressed but noticed he failed to mention another structure in obvious disrepair standing off from the others.
They inquired about the unmentioned building and the castaway turned visibly angry. “Oh,” he said. “That’s my old church. They made me mad. So, I quit going there.” That tired old church joke reveals a deep truth about how we fail God’s demands for acceptable worship. Even when we form a church of one, we can’t get along with ourselves. We break God’s Law. We break the rules we create for ourselves.
You may recall Jesus’ encounter with a Samaritan woman in John 4. She too was concerned about WHERE to worship. She asked him a worship question: Is Mt. Gerizim, where the Samaritan’s worshiped, or the Temple Mount in Jerusalem the correct place to worship? Jesus answered her:
…the hour is coming, and is now here, when the true worshipers will worship the Father in spirit and truth, for the Father is seeking such people to worship him. 24 God is spirit, and those who worship him must worship in spirit and truth.
We learn what Jesus means by worship in truth in Jn. 14:6 when Jesus says to Thomas, “I am the way, the truth, and the life. No one comes to the Father except through Me.” Acceptable worship after Christ has come is not about a place. It’s about a person; it’s coming to the Father, in the Holy Spirit, through the Son. So, we know WHERE and WHAT acceptable worship is.
King David asks, “WHO is the acceptable worshipper?” O I AM, who shall sojourn in your tent? / Who shall dwell on your holy hill? You may recall from 2 Sam. 5:5 that David reigned as king in the city of Hebron for 7 years before conquering Jerusalem. Some time after taking Jerusalem, he brought the Ark of the Covenant to Jerusalem and placed it in a tent on Mt. Zion (2 Sam. 7:2). God’s presence made Mt. Zion, a holy place – the place where God lived with his people.
God’s presence with the Ark prompts messiah David’s question of who can enter God’s presence. He answers with a “liturgical Decalogue,” a list of ten requirements that demand self-examination. It teaches all the people of God to keep covenant, especially brotherly love, with all their heart to secure eternal life. Like Psalm 1, it’s a Torah psalm fleshing out the perfect demands of God’s law. There are barriers between man and God; man cannot barge into God’s holy presence without being consumed by holy fire.
In fact, the worshipper is a resident alien, one who (like Abraham, or Israel in Babylon) sojourns into a land not his own. The worshipper lives in God’s tent only by God’s favor that gives protection, provision, and rest. Only if the sojourner perfectly follows God’s law can he dwell as a welcome guest in God’s house.
HOUSE RULES (15:2-5)
David’s rules for the acceptable worshipper don’t form an exhaustive list. He gives representative answers, not all-inclusive answers. We know this because Psalm 24 begins with a similar question (Who shall ascend the hill of I AM? 24:3) but lists other aspects of holiness (Ps. 24:3-4; Isa. 33:14-17). Isaiah 33 asks, “Who of us can dwell with the consuming fire? Who of us can dwell with everlasting burning?” He replies:
He who walks righteously / and speaks what is right, / who rejects gain from extortion / and keeps his hand from accepting bribes, / who stops his ears against plots of murder / and shuts his eyes against contemplating evil (v. 15).
Blameless, Righteous Actions (2a)
First, the acceptable worshipper must be free of blame, a person of well-rounded and grounded character. This person has no weak spots but keeps all of God’s commandments all the time. Further, the acceptable worshipper not only has a passively upright character but also does righteousness, performs all that God commands. Jesus defined the doer of righteousness as one who feeds the hungry, gives drink to the thirsty, welcomes the stranger, clothes the naked, cares for the sick, and visits the prisoner (Matt. 25:34–39).
Blameless Speech (2b, 3)
The next example of the blameless worshipper is that he or she “…speaks truth in his heart; / 3 …does not slander with his tongue….” In biblical ethics, righteous actions and righteous speech are inseparable. The acceptable worshipper “does no evil to his neighbor / nor lifts up insults against his friends.” The acceptable worshipper of I AM does not insult or vilify other people. Ever. Period.
Jesus in his great sermon on the Law of God said (Matt. 5:21-22):
21 “You have heard that it was said to those of old, ‘You shall not murder; and whoever murders will be liable to judgment.’ 22 But I say to you that everyone who is angry with his brother will be liable to judgment; whoever insults his brother will be liable to the council; and whoever says, ‘You fool!’ will be liable to the hell of fire.”
Offering up another of God’s image-bearers on the altar of your demands and slashing them with your words is murder. When you speak ill of someone else, you are a murderer. There is no exception for the commands of this Psalm. You get no pass because you don’t like some bible teacher’s theology, some fellow church member’s quirks or deficiencies, or the way your next-door neighbor cuts his hair.
Westminster Larger Catechism Q&A 144 explains the demands of 9th Commandment (You shall not bear false witness against your neighbor) as:
a charitable esteem of our neighbors; loving, desiring, and rejoicing in their good name; sorrowing for, and covering of their infirmities; freely acknowledging of their gifts and graces, defending their innocence; a ready receiving of a good report, and unwillingness to admit of an evil report, concerning them; discouraging tale–bearers, flatterers, and slanderers; love and care of our own good name, and defending it when need requires; keeping of lawful promises; studying and practicing of whatsoever things are true, honest, lovely, and of good report.
Here’s what the 9th Commandment forbids (in part!):
all prejudicing …the good name of our neighbors, …holding our peace when iniquity calls for either a reproof from ourselves, or complaint to others; speaking the truth … maliciously to a wrong end, or perverting it to a wrong meaning …speaking untruth, lying, slandering, backbiting, detracting, tale–bearing, whispering, scoffing, reviling, rash, harsh, and partial [criticizing]; misconstructing intentions, words, and actions; … thinking or speaking too highly or too meanly of ourselves or others; denying the gifts and graces of God; aggravating smaller faults …unnecessary discovering of infirmities, raising false rumors, receiving and countenancing evil reports, and stopping our ears against just defense; evil suspicion; envying or grieving at the deserved credit of any, endeavoring or desiring to impair it, rejoicing in their disgrace and infamy; scornful contempt …neglecting such things as are of good report….
If you speak bad things about others, you are utterly unfit to worship God! If you receive other people’s gossip and complaints about others, you are utterly unfit to worship God. If you refuse to rebuke gossips and grumblers, you are utterly unfit to worship God. If you take the truth and spin it against your neighbor, you are completely unfit to worship I AM.
Bruce Waltke’s commentary on Ps. 15 has this illustration of speaking truth in a harmful way (not speaking the truth in his heart):
The old joke has it that a captain wrote in his ship’s log: “The first mate was drunk today.” The first mate complained, “Aye, captain, you didn’t have to write that into the log.” The captain replied: “The truth is the truth.” On the next day the first mate wrote in the log: “The captain was sober today.”
What we say about other people reflects our desire to BE God. We adore being little “g” gods in our workplaces, in the political arena, in church circles, or in the realm of theological correctness. We are desperate to speak our own will into existence by demeaning others. And doing so, even once (just one time only) in our lives, makes us eternally unfit to sojourn on Mt. Zion.
Dr. James Boice, in his work on Ps. 15 claimed the chief sin in the Church of the Lord Jesus Christ is gossip. He wrote:
I think more damage has been done to the church and its work [by] gossip, criticism, and slander than by any other single sin. So I say, don’t do it. Bite your tongue before you criticize another Christian. The great seventeenth-century commentator Matthew Poole wrote, “Pity your brethren; let it suffice that godly ministers and Christians are loaded with reproaches by wicked men—there is no need that you should combine with them in this diabolical work.”
By the way, in verse 2, “speaking truth in his heart” also includes THINKING bad thoughts about someone else even if you keep your mouth shut. Words are what “good people” use to commit murder, whether spoken, written, or thought. There is no escape from God’s righteous demand that you be completely holy in thought, word, and deed to be an acceptable worshipper.
Despises Vile, Fears I AM (4a, b)
Though we don’t vilify others, we do make distinctions between God’s righteous standards and those who openly despise I AM’s wisdom and the teaching of his Torah (Prov. 1:7). David says the acceptable worshipper is one “in whose eyes a vile person is despised, /but who honors those who fear the Lord….” 
The vile person stands in opposition to God-fearers. The acceptable worshipper identifies with all God’s people, not just the ones with whom he has a perfect theological agreement; not just the one’s with whom she is in perfect political alignment. One who fears I AM loves I AM with all his being; she trusts God and obeys his teaching. He does so because he holds I AM in awe, knowing that God holds in his hands life for the pious and covenant-keepers, and death for the disobedient. The accepted worshiper rejects the contemptible, he always honors those who fear I AM.
Worship at Any Cost (4c-5)
The acceptable worshipper, “swears to his own hurt and does not change….”  When she takes an oath, she sticks by her word no matter what the cost. How many of you have taken membership vows at a church (sworn an oath) and then later left because that place just wasn’t meeting your felt needs? Have you ever skipped out on an obligation because it cost you more than you anticipated? You are not fit to worship when you break your vows.
“What do I get out of this deal?” is how we analyze our relationships (work, church, marriage, family, friendships). But the acceptable worshipper NEVER asks that question. He just keeps on giving, no matter the cost. She even lends out her hard-earned money expecting no profit from those who struggle financially. He never makes money at the cost of hurting or oppressing the powerless.
The psalmist closes by promising, “He who does these things shall never be toppled” (knocked over, shaken off the foundation). The worshipper who lives securely with God thinks with righteousness, speaks righteously, and does only righteousness. Period. No exceptions. No “do overs.” No excuses, rationalizations, or self-defense allowed. Be perfect for I AM perfect is I AM’s eternal unchangeable demand.
The entire psalter is arranged to point to Messiah. So, it’s no accident that before the people would sing this Torah song, they would hear this song of David (Ps. 14) first:
2 The Lord looks down from heaven on the children of man, / to see if there are any who understand, / who seek after God. / 3 They have all turned aside; together they have become corrupt; / there is none who does good, / not even one. 
We don’t really believe that, of course, even though Paul says it again in Romans 3. We’re pretty sure we can defend our “mistakes.” After all, we’re good church-going people. So our repentance is weak at best for we are so curved inward upon ourselves we cannot see how horrible are the words we think and speak and the harm we do.
That’s why Psalm 15, a Torah Psalm, follows the universal statement of sin in Psalm 14. Psalm 15 is a demand of perfect righteousness holding up a mirror to our perfect failures designed to show our desperate need for a perfect representative. The early Church sang this psalm on Ascension Thursday in celebration of Messiah Jesus’ ascension into heaven following his death and resurrection. They recognized that only Messiah Jesus was fit to dwell on I AM’s holy hill.
You cannot barge into the presence of I AM as a matter of right. You cannot earn ANY merit from him at all. You have nothing in which to take pride. NOTHING. What do you have that you did not receive? The only things of our own making are angry hearts, filthy mouths, and dirty hands.
No, we need God’s Spirit to lead us into true, humble repentance over our horrible sins and we need the Representative Man, the resurrected and glorified Messiah Jesus, who lived the perfect life God demanded and died for us the eternal death our Torah-breaking requires. If we are to dwell securely in God’s house as citizens and not sojourners (Eph. 2:19), our pride and boasting must be in his one-way love alone. So, St Author of Hebrews writes:
Therefore, holy brothers, you who share in a heavenly calling, consider Jesus, the apostle and high priest of our confession, 2 who was faithful to him who appointed him, just as Moses also was faithful in all God’s house. 3 For Jesus has been counted worthy of more glory than Moses—as much more glory as the builder of a house has more honor than the house itself. 4 (For every house is built by someone, but the builder of all things is God.) 5 Now Moses was faithful in all God’s house as a servant, to testify to the things that were to be spoken later, 6 but Christ is faithful over God’s house as a son. And we are his house, if indeed we hold fast our confidence and our boasting in our hope.
 The Holy Bible: English Standard Version (Wheaton: Standard Bible Society, 2016), Ps 15.
 The Holy Bible: English Standard Version (Wheaton: Standard Bible Society, 2016), Jn 4:23–24.
 The New King James Version (Nashville: Thomas Nelson, 1982), Jn 14:6.
 Waltke, et. al., 296.
 Id., 297.
 The Holy Bible: English Standard Version (Wheaton: Standard Bible Society, 2016), Ps 15:2–3.
 The Holy Bible: English Standard Version (Wheaton: Standard Bible Society, 2016), Mt 5:21–22.
 Morton H. Smith, Larger Catechism of the Westminster Confession Standards, electronic ed. (Greenville: Greenville Presbyterian Theological Seminary Press, 1996), 2.
 Waltke, et. al., 300.
 Boice, 125.
 The Holy Bible: English Standard Version (Wheaton: Standard Bible Society, 2016), Ps 15:4.
 Waltke, et. al., 303.
 The Holy Bible: English Standard Version (Wheaton: Standard Bible Society, 2016), Ps 15:4.
 The Holy Bible: English Standard Version (Wheaton: Standard Bible Society, 2016), Ps 14:2–3.
 The Holy Bible: English Standard Version (Wheaton: Standard Bible Society, 2016), Heb 3:1–6.