I think the other issue that atheists have is that the “teachings” of the Bible were thought up and codified many thousands of years ago; social / moral / cultural etc attitudes have changed massively in that time span, in a way which I would say is generally for the better in terms of tolerance and social harmony (although there are of course many problems in this regard).
What I think some find challenging is the refusal / lack of desire / lack of perception of need to modify accordingly.
I have met and know Christians who are completely tolerant and see it as a flaw in the church, others who interpret things more literally. From my standpoint, I don’t see why an outdated moral guidance / set of rules should triumph over scientific evidence and lived experience to the contrary.
Accordingly, I find it frustrating that people are considered a “sinner” (which to the non-believer can be patronising) for being who they are naturally. The knowledge that many millions of people perceive you as somehow “wrong” or morally questionable for being yourself is (I would imagine) stigmatic in practice for homosexuals. One of my closest friends is homosexual and his upbringing in a catholic society damaged him badly.
I think there is also a quite laudable British quality / attitude of “mind your own business” - if it has no adverse impact on your life, why is it so problematic?
Lastly on this ramble, religious belief and resulting behaviours and opinions are - and long have been - a significant cause for division and antipathy amongst a species whose societies are naturally communal and better-served unified. It has been exploited, sometimes in good faith and often not, to carry out appalling acts of slaughter and wanton violence. History is littered with so many examples that I consider this point trite.
With that said, should somebody be slated / stigmatised for promulgating Christian beliefs, either this particularly point directly or more generally? No; that wouldn’t help and undermines the value of free speech and societal development. But I think it is right - and in the public interest - that such behaviour is scrutinised and discussed. In Guehi’s case it is quite provocative in my view - why does it need to be made public? Aside from being naive and (again in my view) quite selfish, it just seems an avoidable flashpoint.