I'm a Christian, but I would never tell anyone to try to believe in God. It's not something you do by force of will or just decide to do. You may decide to go to church or to participate in similar activities, but belief itself happens freely (or doesn't.)

A therapist having different religious beliefs from mine is not necessarily a reason to me to rule out their being my therapist. It depends on whether or not they try to force their beliefs on me.