You must believe He was sent to die for our sins, once you believe or can come to terms with that then you repent from your sins. The bible still says you must accept this and repent from your sins. Then of course you gotta follow in line, no cursing, drinking (to drunkness) smoking etc all the things that are bad for you.
Also, there isn't evidence of Jesus being crucified? I don't understand the whole, "there MUST be evidence" thing. There were people before/after Jesus being crucified. It just goes back and forth if it was a "cross" or a "T" or whatever. Honestly, who cares what he was ON, it's what it was FOR. You're not suppose to worship this cross, or idolize it or have it in your house as a "show thingy" SMH @ people who do.