 Now, granted, there is an element of faith that we must apply to believe, but Christianity is based on clear facts. Acts 1-3 tells us, again, during the 40 days after he suffered and died, he appeared to the apostles from time to time, and he proved to them in many ways that he was actually alive, and he taught them about the kingdom of God. In the original language, the word for proved in this verse includes the idea of convincing.