John Harper was born into a Christian family May 29, 1872. He became a Christian 13 years later and had already started preaching by age 17. He received training at the Baptist Pioneer Mission in London, and in 1896 he founded a church, now known as Harper Memorial Church, which began with 25 worshipers but had grown to 500 members by the time he left 13 years later.

In 1912 Harper, the newly called pastor of Moody Church in Chicago, was traveling on the Titanic with his 6-year-old daughter. After the ship struck an iceberg and began to sink, he got Nana into a lifeboat but apparently made no effort to follow her. Instead, he ran through the ship yelling, "Women, children, and unsaved into the lifeboats!" Survivors report that he then began witnessing to anyone who would listen. He continued preaching even after he had jumped into the water and was clinging to a piece of wreckage (he'd already given his lifejacket to another man).

Harper's final moments were recounted four years later at a meeting in Hamilton, Ontario, by a man who said:

I am a survivor of the Titanic. When I was drifting alone on a spar that awful night, the tide brought Mr. Harper of Glasgow, also on a piece of wreck, near me. "Man," he said, "are you saved?" "No," I said, "I am not." He replied, "Believe on the Lord Jesus Christ and thou shalt be saved."

The waves bore him away, but, strange to say, brought him back a little later, and he said, "Are you saved now?" "No," I said, "I cannot honestly say that I am." He said again, "Believe on the Lord Jesus Christ, and thou shalt be saved," and shortly after he went down; and there, alone in the night, and with two miles of water under me, I believed. I am John Harper's last convert.

He was also one of only six people picked out the water by the lifeboats; the other 1,522, including Harper, were left to die.