My feeling is, they have a right to their beliefs, just as I have a right not to believe in religion as a whole.
However,I'm not going on national television or standing outside of school refusing to let my DCs go in because the school (rightfully) teaches RE. Likewise, I don't foist my views on my DCs, allowing them to reach their own, informed, opinions.
I worry that we are about to go back to a time when being gay was dirty, disgusting and criminal. As a bisexual woman, I find that incredibly upsetting.
I'm also Catholic, another religion which wasn't keen on homosexuality. It's not like that most of the time now, the Pope actually asked for tolerance recently.
There are many aspects of the Muslim religion which I find troubling, and hope it doesn't become the accepted norm via the backdoor- the way they treat their women and daughters, "honour" and their attitude that underage sex is fine for instance.
Those who have removed their children should be dealt with just as you and I would if we removed our offspring-with a fine for missing school.