How are you?
The word of God says to separate yourself from among them.Why? Because he knows that the same people of the world that we encounter with each day, will pull us back into sin again. We should now walk in the light that the glory of God may shine through us,upon us, and show to the world that we are for Christ Jesus. Yes they may be the only friends you have and you have come a long way with them; but if you are willing to give them up God is willing to send people un your lives that will help you build your faith. If we allow them to pull us back into the world and into darkness what light will begin to shine through us? Not the light if Christ but that light will become darkness. So those company of people you associate with at school , around you, be careful that they don't influence you, but you influence them. No I'm not saying that you cannot be friends with non-Christians but be sure that you don't allow them to cause you to withdraw from God.
1 Corinthians 10:12- Wherefore let him that thinketh he standeth take heed lest he fall
Be blessed.