I think of the great expositor of Scripture Arthur Pink. Before he came to know the Lord he was in what was then called a "Theosophical Society," a kind of forerunner of the New Age movement. Iain Murray titles the first chapter in his biography of Pink, "A Spiritualist Medium Becomes a Christian." As a young man in his early 20s Pink was a rising star and in demand speaker in these Theosophical Societies. He had even been invited to move to India to study more closely Eastern religions.
The Lord still delights in taking skeptical scribes and making them his saints.