Proverbs 13:20 He who walks with wise men will be wise, but the companion of fools will suffer harm
You can tell a lot about a person by the company they keep. I have seen the damage done time and time again by people who once went to church, and still hanged out with their old friends only to find themselves pulled back into the world. Especially when you become a new believer, you can not hang out with the old friends like you used to and think you will not be affected.
Before I became a Christian, I loved hanging out with my friends. We didnt go out robbing people or get drunk but we used to go out at the weekends and go to parties and clubs and generally have a good laugh. But when I became a Christian, my allegiance changed (which was quite hard admittedly) but I knew I had to be around like minded people who loved God and loved his word. I had to throw out all of my old records because at that time, I could not handle it because of the affect it had on me. Looking back now, this was definitely God changing me
Now I am not saying that you should never mingle with non christians or old friends but when they begin to have a negative affect on your spiritual life, then maybe its time to loosen the reins.
This is also so true with ministers of the gospel that hang around together. Of course there are exceptions and but generally you can have a good idea the where a pastor or minister stands theologically by the people that they have to speak at their meetings and conferences and the ministers that they ‘hang around’ with.
The best analogy I can give is if you are a sheep, you feel uncomfortable being in a pig pen and vice versa. If you are comfortable in a pig pen, then it is probably because you are a pig. Do you feel comfortable hanging around with people who constantly swear, get drunk etc. Then it maybe a good idea to examine yourself to see if you are truly saved.
So my advice is find wise people and be in their company as much as possible. It could literally save your life