Drawing a legitimate conclusion ( extrapolating if you will) from information in scripture.
Some of them are

not sure of the exact verses)
Paul makes statements that he cast votes and was on a fast track in Judaism (Galatians i think) but he never implicitly stated he was a full fledged member. If he were, he would have to have been married.
Others are when he mentions "unmarried" as he was. There is a legitimate context where "un" married doesn't mean "single" ( as in never married) but no longer married for any number of reasons. ( some historians make a case that a 'widower" [ male] didn't take that title socially)
Few others that escape my memory right now but basically a circumstantial case but with no definitive "proof" either way.