DC - with respect, I do find your views to be typical of the stereotype about RE teachers, and not the reality! I am an atheistic RE teacher, and there are a lot of us out there. In my experience, out of 9 the RE teachers I have worked with only 4 have a religious conviction... and that is typical of the make up of RE teachers, it is usually half and half, with agnostics being the main "group" ifswim!
I am not quite sure what you think the problem with RE teaching is... you say that it is because "RE promotes the idea that there isn't objective truth" But this leads me to ask you, what is the objective truth? The fact is, that not everything can be proven... and are we really ready to go back down the route of the logical positivists? In my view, this would lead to a very narrow view of life, let alone religion...
However, even this view misinterprets what RE should be about. Part of it should be about students finding out the answers for themselves. Yes, often there are no definite answers in RE.. but then we cannot prove whether there is life after death or not, neither can we prove whether capital punishment is right or wrong - what counts is having reasoned opinions, based on knowledge and thought! But isn't this is exactly the point you are making? In too many of our school subjects these days, with so much emphasis on knowledge, students are often not given the opportunity to think for themselves / make their own opinions, and as you say, that leads to the very sad outcome that people do fall foul of 'bad thinking'. However, RE often asks questions that do make children think and consider their justifications for why they think what they think. Typical exam questions might ask students whether they think capital punishment / abortion / euthanasia is right or wrong and to give strong foundations for their opinions. Isn't this the kind of thinking that you want people to do?
Also, I'm sure why you think Jesus was not a historical figure. Have you ever read the 8 indisputable facts by EP Saunders? Even as an atheist, I recognise that there was a bloke called Jesus - only I differ on who I think he was!
However, I do agree with you that we need to encourage more people to think for themselves, and it is sad that too often kids don't. TBH, we need more kids to do more philosophy (whether that means RE changes to incporate philosophy more) or whether it should be taught as a separate subject, I'm not sure... but like you I despair at the poor and illogical thinking I see in my students, but then I also teach Critical Thinking, so I guess I would