In my late twenties I finally laid to rest the pessimistic, rapturistic view of the future in which I had been raised, and adopted a victory-oriented view of the kingdom of Christ in history before the Second Coming. It happened after a struggle and with much serious study and prayer. What finally pushed me into the postmillennial camp was the Biblical doctrine of the preaching of the Word of God. What the Bible taught about the nature and triumph of the preached Word made any defeatistic, pessimistic view of the future of Christ's kingdom in history impossible.
It was what the Sixteenth Century Puritans and the contemporary French Calvinist, Pierre Marcel's book, THE RELEVANCE OF PREACHING, said that God used to help me see what the Bible taught about the nature and power of preaching.