When my youngest (from here on called BtY) was in 4th grade, he was used to bullying and let it kind of roll off his back (one of the advantages of his ASD - he didn’t let things bother him because other people didn’t matter. ) One of his friends, a girl whose family was close to ours, was being bullied by several girls in her class. She was talking about out one afternoon when I picked them up. BtY turned and told her, "This is what you’ve got to do. You have to think of them like a cactus. They’ve got all the prickly bits on them. And since they’re prickly, you stay away from them. Because you don’t have to care what a prickly cactus thinks about you. "
Cacti have become our family code for bullies and other jerks.
I don’t know about pithy, but I used to tell my kids “If you insist on being uninformed, you’ll likely end up uniformed.” Meaning that the likelihood of being in McDonald’s or other company/military garb is higher if you are uneducated. My youngest ended up working for Menard’s for 17 years, and ruefully told me that he really wished he had gone to college instead of joining the workforce so young.
I also told my kids “Everything you do in life has a consequence. You just have to decide whether that consequence is going to be a good one or a bad one, depending on what action you choose to take.”
There’s a Yiddish expression that translates roughly as “When the prick stands, the brains fall to the ground,” but is more eloquent than that. World history in a nutshell.
I think if we combine that with the spirit of the OP we end up with something along the lines of:
A personal religious belief is like masturbation; nothing to be ashamed of but nothing to be particularly proud of either. And not suitable for public demonstrations.