Carl Cannon writes at RealClearPolitics:
Although John Newton’s birthday was July 24, 1725, after he turned 23 the day that meant more to him was his “rebirth,” March 21, 1748. That was the day he rediscovered his faith. He gave up drinking and swearing and carousing, and began to study for the ministry.
In the early 1760s, he was assigned a church. In the early 1770s, he sat down at a desk in his attic and penned these words:
Amazing grace, how sweet the sound
That saved a wretch like me.
I once was lost, but now am found,
Was blind, but now I see.
Fully accepting the implications of faith took a long time. What I mean by that is that even after becoming a Christian, Newton transported slaves as a sea captain for many years.
Even after writing “Amazing Grace,” which would become an anthem of liberation for slaves America, it was more than another decade before Newton announced his opposition to slavery and joined forces in London with William Wilberforce.
This lag time is often airbrushed out of the story by modern day evangelicals. This defensiveness is understandable, but it doesn’t make John Newton’s faith journey any less remarkable.
“Newton did eventually grow into his conversion, so that by the end of his days he actually was the godly man one would expect to have penned ‘Amazing Grace,’” writer Barbara Mikkelson once noted.
“But it was a slow process effected over the passage of decades, not something that happened with a clap of thunder and a flash of lightning,” she added. “In Newton's case, the ‘amazing grace’ he wrote of might well have referred to God’s unending patience with him.