Onagar
The issue with denying the existance of Jesus (and the existance of other later prophets such as Mohammed) is that there are too many contemporary sources saying the same thing for it to have been made up (one argument is that most people were illiterate then and all accounts are oral- the bit about illiteracy is true but there are many writings from that time- not just religious texts- which mention the existance of Jesus, and latterly Prophet Mohammed).
As such, the majority of Theologian scholars (not all of whom are religious btw)dont disagree that these people existed and that they were spiritual men. Jesus told people he was the son of God and Mohammed that he was a prophet. The issue is whether you believe this or that they were just charlatans/ confused.
Therefore to tell people "it's all made up" is wrong. The issue is the interpretation and of course, translation of scripts, changing meanings of words over time and ambiguity have led to arguments over what was intended- one of the most obvious examples is the debate over whether the Qoran requires muslim women to cover their faces.
So anyway, that 's the historian in me talking. Where does that leave me religion wise? I am nominally CofE by upbringing and current faith. What does that mean to me? Do I believe that we go to heaven when we die? Not really if I'm honest. I wish I did as then I would be much less scared of dying but you cant force faith, just as you cant deny it. Do I think that Jesus, whoever he was, had some good teachings about how to live life not just in your best interests but to the wider good? Yes, I do. I also think that Islam has some pertinent teachings, especially it's emphasis on looking to yourself for improvement first, not casting around to find others to judge.
On that basis, I am happy for my children to learn about religious teachings, because I think it provides a good framework. I'm not bothered about them sticking to Christian teachings as I do believe that it's probably a case of "many paths".
Anyway, sorry for the long post. Not trying to lecture anyone, and I do recognise that there are many many problems with organised religion. I'm just saying that I think people feeling that theres a line in the sand and they have to either believe everything in the bible/Qoran unconditionally or alternatively say "Stupid sky fairy is just made up" is wrong.
We'll none of us ever know till we die anyway.