Impossible, and not in line with the American founding principle of religious freedom.
However, that doesn't mean that nothing can be done to curtail Muslim terror in the USA.
I read in the .uk article that the shooter had previously pledged allegiance to a terror group.
This should be a no-brainer to remove his ass from this nation. I cannot believe a person swearing to terror groups can get a gun permit. His ass should get sent out, period.
There is no stopping the guns, they're out of the tube.
There is no stopping any religion because of violence, because ours will be next.
There sure can be kicking their asses out, if they have ANY association with terr'ists. This is a massive attack on US soil. This is a very big deal.