On April 25, 1951, the gospel came home to C. S. Lewis. This fascinating event does not seem to be well known, even among admirers. Yet Lewis refers to it no less than five times in volume three of the Collected Letters of C. S. Lewis, which covers the final years of his life, 1950 to 1963.
From a letter to St. Giovanni Calabria in December 1951:
During the past year a great joy has befallen me. Difficult though it is, I shall try to explain this in words. It is astonishing that sometimes we believe that we believe what, really, in our heart, we do not believe.
For a long time I believed that I believed in the forgiveness of sins. But suddenly (on St. Mark’s Day [April 25]) this truth appeared in my mind in so clear a light that I perceived that never before (and that after many confessions and absolutions) had I believed it with my whole heart.
So great is the difference between mere affirmation by the intellect and that faith, fixed in the very marrow and as it were palpable, which the Apostle wrote was substance. . . .(p. 151-152)
In 1956, Lewis remarked to Mary Van Deusen, concerning the gospel:
I had assented to the doctrine years earlier and would have said I believed it. Then, one blessed day, it suddenly became real to me and made what I had previously called “belief” look absolutely unreal. (p. 751)
--both quotes from the Collected Letters of C. S. Lewis, vol 3
Some remarks made by Dane Ortlund in a blog post concerning these quotes:
Lewis was 53 in 1951. He had 12 years left to live. He had been a Christian for many years—a fruitful Christian for many years. And grace came home to Lewis one day in 1951 in such freshness and power that his previous grasp of grace seemed “absolutely unreal.”
By 1951 Lewis had written The Pilgrim’s Regress, the Space Trilogy, Mere Christianity, The Abolition of Man, The Problem of Pain, Miracles, and much more. Seasoned Christian leaders never outgrow the need for a fresh outpouring of visceral awareness—a renewed “sense of the heart,” as Jonathan Edwards called it—of gospel grace.
-- source: here