This is a bad question, I think. Who is this "left" or "the left" that you're talking about?
The truth is, there are some leftists and multiculturalists who do seem to excuse homophobia on the part of intolerant Muslims, for various reasons.
But there are other leftists -- especially militant atheists, and especially gay leftists and feminists -- who think that anti-gay attitudes always are wrong.
Your're treating them as if they're all the same -- and they're not.
You're also ignoring the fact that some leftists -- not all, but some -- are Christians themselves.
Are you doing this mostly to attack "the left," or doing it mostly to attack Muslims and justify the idea of religious discrimination by the government -- which goes against the US constitution?
-- democratic socialist for religious liberty and against homophobia
"Love your neighbor as yourself ... Judge not, lest you be judged" -- Jesus of Nazareth, in the Gospel According to St. Matthew