Do not be deceived: “Bad company corrupts good morals.”
— 1 John 3:17
Bad companions ruin good character. How true that is for people of all ages, perhaps especially young people. Take heed whom you select as friends. One of the wisest bits of advice that you could possibly have is: choose friends that are more godly than you are.
If you want to know how spiritual or how holy you are, take a look at your friends, because they are a very good reflection of your spiritual growth. Birds of a feather, you know, flock together. How spiritual are your friends? I can tell you this: they are probably about as spiritual as you are. Jesus went among sinners, you say. Yes, but he went to give them the Gospel, not to get fellowship and companionship from them.
In Psalm 1, David contrasts the godly with the ungodly. The godly man not only spends time meditating and reflecting on the Word of God, he shuns the corruption that comes from the company of mockers. We need to choose our friends wisely, so that we can build each other up, not bring each other down.