Ps. 26:4-5 I do not spend time with liars or go along with hypocrites. I hate the gatherings of those who do evil, and I refuse to join in with the wicked.
The Psalmist shows us a sure fire way to keep our souls out of trouble with God. We stay away from those who would lead us into sin. When we choose carefully those whom we spend most of our time with, we can avoid many of the pitfalls of sin.
It is a waste of time to hang around with those who are liars. You cannot trust those who do not have the integrity of heart to tell the truth. You can be easily deceived by them. Listen to them and you will find it difficult to distinguish that which is true from that which is false.
It is not a good idea to spend time with those who profess one thing and live another. One can easily fall into the trap of justifying one's own sinful behavior by believing that if it's okay for someone who professes to have faith to do it, it's okay for him to do it. It is never okay to do what you know God says not to do just because someone else is doing it. Sin is sin and will always be sin even if the whole world does it.
We can keep our souls pure before God by not hanging around where sinners hang around. We should despise being in places where we know people are sinning openly. It ought to shame us to be where sin is displayed and promoted. When we hang around in the cesspool of sin, we will more than likely fall into it.
A pure heart takes charge of his soul. He refuses to compromise the truth. He refuses to expose his soul to the ways of the wicked. He surrounds himself with people who can help him stay pure instead of hindering him. He just says "no" to sin and means it.