Newman himself was raised to believe that Rome was the Antichrist predicted in scripture, but he also opposed "ultra-protestantism," which discarded everything Roman. His own reading and study was leading him to a different direction than originally intended. To justify the Via Media position, he had gone back to early Church history.

Little by little, Newman's objections to Roman Catholicism were breaking down under extended examination. "Catholicism," he would later write, "is a deep matter—you cannot take it up in a teacup." He was coming to see it, rather than his own Church, as the true successor to the Apostles. There was nothing, he insisted, "which the Church has defined or shall define but what an Apostle, if asked, would have been fully able to answer." As his objections disappeared, he moved closer to converting.

On October 9, 1845, at age 44, John Henry Newman was finally received into the Roman Catholic Church. His Anglican life was ended. "I am going to those whom I do not know," he wrote, "and of whom I expect very little—I am making myself an outcast, and that at my age." It was a sacrifice in which he felt "no pleasure."

Newman's conversion shocked many, both Catholic and Protestant. For a clergyman to do so meant starting completely over, giving up a comfortable position. For many converts, it involved the loss of lifelong friends, even ostracism from family. (Anti-Catholicism was still a powerful element in 19th-century England.) Newman found many lifelong relationships abruptly ended.

The reason Newman converted, he wrote, was that "I consider the Roman Catholic Communion the Church of the Apostles." For Newman, Roman Catholicism didn't just claim to offer the truth; it was the Truth. He had dedicated his whole life to the pursuit of truth, wherever it might lead. This was the theme of his greatest poem, "The Pillar of the Cloud," written in 1833:

Lead, kindly Light, amid th'encircling gloom, lead Thou me on!
The night is dark, and I am far from home; lead Thou me on!
Keep Thou my feet; I do not ask to see
The distant scene; one step enough for me.

I was not ever thus, nor prayed that Thou shouldst lead me on;
I loved to choose and see my path; but now lead Thou me on!
I loved the garish day, and, spite of fears,
Pride ruled my will. Remember not past years!
So long Thy power hath blest me, sure it still will lead me on.
O'er moor and fen, o'er crag and torrent, till the night is gone,

And with the morn those angel faces smile, which I
Have loved long since, and lost awhile!

Change is never an easy thing, but for Newman it was an essential component of authentic personal growth. "In a perfect world it may be otherwise," he wrote. "But here below to grow is to change, and to be perfect means to have changed often."