One of the most difficult things to do, if not impossible, is convince a secular Jew of a religious reality. They just don’t not believe, but they lack the intellectual tools to believe. It’s much easier to admit that they don’t know why something is happening than it is to agree that something happened for religious reasons.
Most of the times it’s just a yetzer hara to have no reason to become religious. They think that ignoring the truth makes the truth disappear, and that it will never catch up with them. Other times they just can’t believe because they can’t their head around it, being limited in the kind of knowledge that allows such truths to come in.