He was the founder of the Yoido Full Gospel Church (Assemblies of God), which he started in a tent with 5 people (including his future mother-in-law Choi Ja-shil and her children as its first members), which eventually became the world's largest congregation, with a membership of 830,000 (as of 2007[update]).

At the same time, he began frequenting an American army base near his school, and learned English from soldiers whom he befriended.

Sensing God calling him to the ministry, Cho began working as an interpreter for the American evangelist Ken Tize.

[6] In March 2011, Cho became a subject of controversy when he reportedly made comments suggesting that the 2011 Tōhoku tsunami "could be a warning from God to Japan, which has become an increasingly materialistic, secular and idol-worshiping country."

The prosecutors began an investigation of Cho's alleged embezzlement of 23 billion won ($20 million USD) from the Yoido Full Gospel Church's funds.

A national broadcaster, MBC, released a documentary that claimed the money had been used to buy properties for Bethesda University in Anaheim, California, United States, which Cho founded.