“The righteous should choose his friends carefully,
For the way of the wicked leads them astray.”
Proverbs 12:26
“Do not be deceived: ‘Bad company corrupts good morals.’”
1 Corinthians 15:33-34
As children of God, we must be careful who we associate with. If we are friends with the world, we will decay towards God. Does he not say, “Do you not know that friendship with the world is enmity with God? Whoever therefore wants to be a friend of the world makes himself an enemy of God. Or do you think that the Scripture says in vain, "The Spirit who dwells in us yearns jealously"? James 4:4-5.
A good reason why this is so dangerous for us can be found in Romans 7. Paul talks about the war we are in, the war between our hearts, which are set on God, and our flesh, in which sin dwells, and which, as a consequence, is dead. Our spirits wish to follow God, but we are still in the body, and still must be careful to “put to death the deeds of the body,” Romans 8:13.
The world, however, sees no need to put to death the deeds of the body, rather, they revel in them. If then we are friends with the world, how much easier it is for temptation to overcome us, how easy it is for us to become entangled in the world again, for our flesh desires these very things for us. By being around the world, we are playing with fire, and, “A little leaven leavens the whole lump,” Galatians 5:9. If we let a little in, how it may grow, how corrupted we may become!
Jesus said, “The spirit indeed is willing, but the flesh is weak,” Matthew 26:41. We don’t need to make matters worse for ourselves by being around the very thing which our flesh desires for us.