I tend to try to have a "don't be an asshole needlessly" attitude when it comes to dealing with religious beliefs that no one is trying to impose on me, but there's no requirement for people to share that attitude. Beliefs cloaked in religion shouldn't be granted automatic immunity from scrutiny, and nor should the sometimes powerful institutions run by people, not angels or saints, around which the various religions are organized. While genuine bigotry exists against people of various faiths which is the equivalent to the kind of bigotry which exists against gays or African-Americans (involving unfair symbols or stereotyping rooted in historic oppression, assigning unshared beliefs to an entire group, etc...), mocking or having contempt for actual religious beliefs isn't by any reasonable definition "bigotry." It's simply heated disagreement, and as with disagreements about politics, or sports, or whatever, sometimes people who disagree with each other use mockery and insults in their discourse. Religious people may think that their beliefs about religion are on a different level than these things, but, you know, I don't really agree with that.
And that's the basic issue. We disagree about things. We don't all share a belief in God, or the supernatural, or the spiritual plane, or whatever. Those who believe in these things don't agree on the details. There are a tremendous variety of belief systems in this country and across the world. The tendency to divide people into "faith" and "non-faith" has, as I wrote, obscured these differences, but the fact is that disagreement within "communities of faith" is no different than disagreement between religious and non-religious people. While I think there are those who genuinely believe in a "many paths to God" kind of worldview (and I have no opinion on whether that's theologically sound within the Christian or any other tradition), plenty of people don't actually share that worldview. They believe "other" beliefs are wacky, or stupid, or nuts, or contemptible, or immoral, or likely to lead to eternal damnation, etc.
This is also a reasonable time to differentiate between offensive and "offensive." If something is offensive to you then you have a genuine emotional reaction. If something is "offensive" then you imagine that maybe others have taken offense, or you find it offensive in some abstract sense which hasn't actually caused you any psychic distress. If you find something "offensive," as opposed to actually being offended, then you're probably just seizing on something which you perceive can be used to further whatever agenda you already had.
55 minutes ago