> And if the religion condones crimes against humanity?
No. If you want to block people who say they are against homosexuality, that might be legal. If you want to block people who say their religion is against homosexuality, that's not legal.
The subtle differences matter. Similarly, if you're hiring for a warehouse job, you can discriminate against people who cannot safely lift 50lb packages repeatedly. You cannot discriminate explicitly against people in wheelchairs, even though that group in general will have a lot of trouble lifting 50 lb packages overhead.
All we'd have to do is ask:
What do you think should be done with homosexuals?
What do you think should be done with Israel?
and we'd get more than enough information to keep 90% of a certain religion out of here, without directly doing that.