To become canonized as a saint, a perfect track record isn’t required (or possible). Hence, being sinless isn’t on the list. So, what is required for sainthood?
Two verifiable postmortem miracles
Note: Canonization (sainthood) requires two miracles, whereas beatification (blessed) requires only one.
Evidence of having led an exemplary life of goodness and virtue worthy of imitation, having died a heroic death (martyrdom), or having undergone a major conversion of heart where a previous immoral life is abandoned and replaced by one of outstanding holiness
Formally declared saints are chosen ultimately by the pope, but only after a thorough investigation of the life, writings, and legacy of the saint candidate. No stone is left unturned. Testimony from witnesses and experts, physical evidence, and the entire life of the person is examined with fine detail. Every skeleton in the closet is taken out, and all dirty laundry looked at — if any exists, that is.
