The First Presbyterian Church of Peoria was founded on April 10, 1892 when Peoria was four years old. It was the only church in Peoria. With a small membership of nine charter members, procuring the services of a regular minister was a tedious process. It was September 1893 when young Henry Adelbert Thompson was sent by the Presbytery of Arizona to serve the Peoria church. The young man was a prime example of the gospel he so earnestly preached. He was deeply involved in The Christian Endeavor movement, which had been founded in 1881.

No sooner was he settled in Peoria than the young minister was given several more charges to add to the one in Peoria. It was necessary then to divide his time to service a wide circuit. The new assignments took him 85 miles northwest to Gila Bend, Wickenburg and Congress mining camps, and southeast 65 miles to Casa Grande and Arizola.

Dividing his time, Thompson preached two Sundays a month in Peoria and the remaining time in the other areas. Any fifth Sundays were preached in Peoria, his main charge, where services were held in the little schoolhouse built in 1891. He was equal to the task and went about his rounds in the "wild" country on a spirited steed with a six shooter strapped around his hip. Much of his studying was done by campfire light, as his journey between commissions took him across an Indian reservation into the mining camp territories of Wickenburg and Congress.

An article in the Phoenix Gazette on March 12, 1895, by Col. McClintock paints a detailed picture of the way in which the parson discharged his duties:

"Religion in the saddle is a reality in Arizona…The Rev. H.A. Thompson (is) delegated by the Presbyterian Board of Missions to carry the gospel into the hamlets of central and southern Arizona.

"Mr. Thompson is a young man, full of health, vigor and enthusiasm in the cause, yet quick to adapt himself to his environment. Clad in the usual frontiersman apparel with spur on heel and revolver at belt, mounted on a powerful nag that steps well out and jogs his 40 miles a day, the dominie looks in few respects different from the average ‘cowman' encountered on the trails that lead out into the wilds. His work is therefore all the more popular and there is no doubt that he, who cheerfully accepts the hospitalities of miner or ranchman, does not disdain straight bacon and black coffee, or a homely pipe by the fireside, is far more able to carry to the masses the word and deed of righteousness than he who sets himself forever upon a pinnacle of theological isolation."

Rev. Thompson became the Secretary of the Arizona Christian Endeavor Union, and was also made Superintendent of Christian Endeavor work in Arizona.

Largely because of his efforts, a state union was organized. He was considered one of the spiritual giants of the land.

He was ordained in April 1897 when he passed his examination before the Arizona Presbytery with great honor. He became engaged to Alice Mann whose parents, Hiram and Jennie Mann, were instrumental in founding the church he served. In September 1897, he returned to Cincinnati, Ohio, to finish his education at the Lane Theological Seminary.

He and his fiancé were married in 1900, and returned to Peoria in 1911 with their five children.