No comparison between the two. Sharing his faith includes a condemnation of their lifestyle and their belief system and that's not acceptable in the workplace - and it's not acceptable anywhere that someone doesn't want to hear it.
You are right, about only one thing there, they (each individual in question) need to express they dont want to hear it, and then it has to keep happening
AFTER the person has said no, that didnt happen here.
He will win this case if its as stated in the op.
Their belief system, should be acceptable, if they are allowed to discuss their own family - untill someone tells them they dont want to hear it or arent interested.
What YOU qualify as a relevant belief system doesnt mean a hill of beans in this.