There is no other explanation for it. Only by the grace of God does Matthew make this transition. Though, it wasn’t easy to find the courage.
Remember, he was one of ten disciples who went into hiding when Jesus was crucified. Their seclusion lasted until Christ came to them, revealed himself to them, and then proved himself to Thomas.
Even after Matthew’s own transformation and salvation, and all that he had personally witnessed, sharing the Good news terrified him, initially. He had been a fan and disciple of Christ for a few years, but he wasn’t yet a Christ follower. Eventually, though, he agrees to risk his life, to lose it once again, so that he would gain eternal life — and give that encouragement to us, too!
Matthew wrote his testimony to prove that Jesus was and is the fulfillment of Jewish prophecy. That He is the Messiah. This is why he starts with genealogy. And it’s why he quotes more Old Testament scripture than the other Gospel authors.
Thank you, Matthew. Your courage and conviction helped change the course of history. I know it’s changed mine.