Welcome!
Yes, it can be confronting to realise that those we considered to b our friends when in the org, are nothing more than conditional associates who shared a common faith...no more, no less. So although we thought of them as our friends, they soon disappear when we stop attending.
However, it's not all bad! In fact, once free of the shackles of those people, you are free to REALLY get to know "worldly" people. And guess what? Most are actually very nice!
Most people just want to interact nicely with one another.
Be warm and approachable. (Be careful too) But simply showing kindness and politeness to those you interact with is the start.
I read a good quote that said "a simple hello can be the start of something wonderful"