Sometime in the spring (Trinity Sunday was May 22 that year, 1929) Lewis came to believe in God, though not yet in Christ:
You must picture me alone in that room in Magdalen, night after night, feeling, whenever my mind lifted even for a second from my work, the steady, unrelenting approach of Him of whom I so earnestly desired not to meet. That which I greatly feared had at last come upon me. In the Trinity Term of 1929 I gave in, and admitted that God was God, and knelt and prayed: perhaps, that night, the most dejected and reluctant convert in all England. I did not then see what is now the most shining and obvious thing; the Divine humility which will accept a convert even on such terms. The Prodigal Son at least walked home on his own feet. But who can duly adore that Love which will open the high gates to a prodigal who is brought in kicking, struggling, resentful, and darting his eyes in every direction for a chance of escape? The words compelle intrare, compel them to come in, have been so abused by wicked men that we shudder at them; but, properly understood, they plumb the depth of the Divine mercy. The hardness of God is kinder than the softness of men, and His compulsion is our liberation.
(Surprised by Joy, Chapter 14)