My thoughts on your questions Karlam -

Should I leave church before making a stupid mistake?

No. Nothing's happened. No reason to leave.

Should I date someone else to get my mind off of him.

No. This is never a good reason to start a new relationship. If you're going to date someone, date someone because you're wanting to start a new relationship, not because you're using your date as a decoy for your feelings.

Should I not avoid him and see how things turn out?

I wouldn't suggest avoiding him.

Impossible to say if he "likes" you - he doesn't even know you and you're probably hiding and aloof around him.

You have one of 2 choices:-

(a) Listen to your intuition and some of the reasons that you have stated for not starting / contemplating / even thinking about entering a relationship with him

(b) Try to get to know him better through mutual friends at the church; maybe a bible study class you two can go to or something