There is no verifiable evidence that anything attributed to Jesus was true.
Oh there's loads of
evidence - like the Gospels and NT, like a few million changed lives, like the fact that Christianity is a major world religion, the Bible has been translated into many languages and people have given their lives for what they believe.
Surely if he had resurrected he would have stuck around on earth
He did - for 40 days. He taught his disciples during that time and answered questions, so that some of them were well qualified to write it all down and produce documents about his teaching and reason for coming.
instead of conveniently disappearing up to heaven, and making the Christina religion a matter of faith rather than substantiated fact?
There are a number of facts that substantiate the Christian religion. Apart from those I've already said, we can confirm that various places that are mentioned in Scripture existed, or still exist, and there is some archaeological evidence. Jewish authors and writings confirm people such as Moses and David - Jesus quoted both of these.
The things that require faith are that there is one God, who is Spirit and who wants a relationship with each one of us; that such a relationship was impossible because of our sin - we messed it up, basically - but that he sent Jesus to offer his life so that we can be forgiven. It requires faith, and humility, to accept that we can't get to heaven by ourselves and by doing things ourselves; we need Jesus. It takes some faith to believe in the resurrection, though as no corpse was ever produced, and no one could stop Christians from declaring that he was alive and they had seen him - even beatings and imprisonment did not stop that - I feel you'd need just as much faith to believe that he stayed dead, or that he revived somehow and escaped from a sealed tomb as you would to believe that he was raised from the dead by God. We need faith to talk to God and trust that he will answer, even if we don't like the answer at the time.
There are many things in this world which require us to have faith, if you think about it.
We have faith that people produce our food correctly; I don't know of anyone who demands their meat is put under a microscope to prove that there are no germs, before we buy it from the supermarket. If we buy a ready meal, we have faith that it contains the ingredients the makers say that it contains. We have faith that our partners will cook our food correctly and not try to poison us. If we are married, we had faith when we made our vows that our partner would keep them.
We have faith that the money we hand over will be accepted to pay for our various goods - that we won't be sent to prison for paying for an ipad with paper.
We have faith that our electrical appliances and gadgets are wired correctly, and that anything we buy - whether online or not - will do what it is supposed to do and not blow up/wear out/collapse the minute we use it. We make plans ahead of time and trust that when we feel tired and go to sleep, that we will wake up the next day. I have faith that you exist - not as a piece of Blue cheese, but as a real person. If you told me stuff about your life, I'd have no reason not to believe it - even though I've never seen, nor met, you.
And whether they admit it or not, everyone has faith in something - in horoscopes, fortune telling, money, good looks, qualifications, or that there is no God and human beings, or fate, are responsible for our lives and destiny. People who choose not to put their faith in God, are more than likely quite happy to put it in something else.