Psalm 15

"Entrance Liturgies"

Per the study notes in both versions of Scripture I study from (Reformed Study Bible, and New King James Study Bible)  this is one of the poems/songs know as entrance liturgies.  The people would ask questions about what was personally necessary for one to enter the tabernacle, and the priest would answer back.
(See also Psalm 24:3-6,  Isaiah 33:14-16)

Notice that all of the requirements involve practical living.....rather than ceremonial ritual, or liturgy.  It wasn't the one who brought the right sacrifices, or an abundant offering, or wore the right clothing, or had the right pedigree, or said just the right things.

Who may come into the presence of God?    The one who:
   walks uprightly
   works righteousness
   speaks the truth in his heart
   does not backbite with his tongue
   does no evil to his neighbor
   does not take up or receive a reproach against his friend
   who despises a vile person
   who honors those who fear the Lord
   who swears to his own hurt (doesn't falter, keeps his word even when it isn't to his advantage)
   who doesn't exploit his brother by charging interest on a loan (which was meant to relieve extreme need)
   who doesn't take bribes against the innocent.

First thought:   Do unto others as you would have them do unto you.

"who speaks the truth in his heart'  This pushes buttons that make me want to jump on my soap box.
  Note that nothing is said about speaking untruths.  But the internal realm of the heart is where this must be nurtured.  I cannot find it now, but elsewhere in Scripture we are told that out of the abundance of the heart the mouth speaks.  You cannot tame the tongue without taming the heart.  This, I believe is why this requirement is listed before the next one.

In my mind this screams  REALITY.   Know and dwell in reality. Think rightly about God, others, and yourself.  This takes effort.  Lots of it.  Especially in the times we live in. Our society does little to encourage living in reality. Think of the fantasy video games many spend hours participating in daily.  Or....how 'bout the unrealistic entertainment we choose to fill hours with on our tv?  Movies and shows that are far from realistic, and even glorify sin, yet we turn a blind eye to that and fill our senses and minds with such garbage!  You cannot speak the truth in your heart if you fill it with lies!

How about our thoughts?  I have been convicted about having conversations in my mind with others that perhaps have hurt me, or I am angry with.....conversations that have not happened and probably won't, yet the next time I see that individual, my attitude toward them is shaped by that unreal, imaginary conversation I had in my head!

I run to Philippians 4:8   Whatever things are TRUE, noble, just, pure, lovely, of good report; if there is any virtue, or anything praiseworthy, meditate (think on, mull over) these things.

The one who may enter God's presence recognizes evil and reacts to it, but honors those who fear the Lord.

He who does these things shall STAND (never be moved).   Remember Psalm 1?