You can read the full retelling of his conversion here, but I’ve pasted sections of the article below that chronicles the night JI Packer became a Christian:

On Sunday, October 22, 1944—seventy years ago today—it is doubtful that anyone noticed a soft-spoken, lanky, and decidedly bookish first-year university student leaving his dormitory room at Corpus Christi College and heading across Oxford for an evening Christian Union service at a local Anglican church.

18-year-old Jim Packer had arrived at Oxford University less than three weeks prior, a single suitcase in hand, traveling east by train from Gloucester using a free ticket available to family members of Great Western Railway employees.

He later described himself at this stage of life as ”immature,” “shy,” “introverted,” “awkward,” “intellectual,” and an “oddball.” He was an “outsider” who was “bad at relationships” and “emotionally locked up.” He was also a “churned-up young man, painfully aware of himself, battling his daily way, as adolescents to, through manifold urges and surges of discontent and frustration.”

Packer came from a lower middle-class background and a nominal Anglican family that went to St Catharine’s Church in Gloucester but never talked about the things of God or even prayed at meals. As a teenager Packer had read a couple of the new books coming out by C. S. Lewis (fellow and tutor in English literature at Oxford’s Magdalen College), including The Screwtape Letters (1942) and the three BBC talks turned pamphlets that would later become Mere Christianity (1942-44). During chess matches with a high school classmate—the son of a Unitarian minister—he had defended Christianity.

Packer thought of himself as a Christian. But the events of that evening would convince him otherwise.

On this cool autumn evening, he made his way west across Oxford, past Pembroke College, and into St Aldate’s Church, where the Christian Union occasionally held services. The lights in the building were dimmed so that the light emanating from the building would be no brighter than moonlight—a recent relaxation of England’s “blackout” regulations to avoid air-raid attacks in World War II.

The service began at 8:15 PM. The preacher was an elderly Anglican parson named Rev. Earl Langston, from the resort town of Weymouth. The first half of the forty-minute sermon consisted of biblical exposition that left Packer bored. But the second half was a personal narrative of how Langston had been converted at a boys’ camp. The key component of that conversion had been a challenge posed to the youthful Langston by a camp leader as to whether or not he was a Christian. Langston had been jolted by this question to conclude that he was not actually saved. That, in turn, led to his coming to personal faith in Christ as Savior.

This autobiographical narrative was riveting to Packer, who had entered Oxford believing himself to be a Christian. Packer suddenly saw his own story in Langston’s narrative and realized that he was not a Christian. It was a traumatic realization. It was accompanied by an imagined picture that Alister McGrath reconstructs as follows:

He found a picture arising from within his mind. The picture was that of someone looking from outside through a window into a room where some people were having a party. Inside the room, people were enjoying themselves by playing games. The person outside could understand the games that they were playing. He knew the rules of the games. But he was outside; they were inside. He needed to come in.

Packer was particularly convicted by the latter awareness: “I need to come in.” So by the Spirit’s prompting he came in. 

(HT: JT)