We are commanded by Jesus to share the gospel. And for those who refuse to do what their Lord says do not really submit to Him as Lord. Also we want...
to share the gospel. If you believed that you had made the greatest discovery in man-kind you too would want to share it. Especially if it meant the destruction...
of humankind and that you had found the answer that would save them. Does this seem "reasonable" to you?
If the person asks where's the proof for God/Jesus/Christianity, go here.