Kip McKean, a key figure until 2003, expanded the church from Gainesville to Boston and it quickly became one of the fastest growing Christian movements with a heavy focus on US college campuses.

The church's emphasis on and system of discipling during the period of McKean's leadership was the subject of particular criticism, with some ex-members alleging that it involved the humiliation of vulnerable members.

Centered on the University of Florida, the program called for a strong evangelical outreach and an intimate religious atmosphere in the form of soul talks and prayer partners.

[13] Born in Indianapolis,[14] McKean completed a degree while training at Crossroads, and afterward served as campus minister at several Churches of Christ locations.

[16] David G. Bromley and J. Gordon Melton, sociologist and historian of religion respectively, note how International Churches of Christ grew quickly in the 1980s, but that "Even as ICOC developed, however, its relationships with several established institutional sectors deteriorated".

[citation needed] Also in 1988, McKean selected a handful of couples that he and Elena, his wife, had personally trained and named them World Sector Leaders.

[10]: 419  The movement was first recognized as an independent religious group in 1992 when John Vaughn, a church growth specialist at Fuller Theological Seminary, listed them as a separate entity.

[8][12] TIME magazine ran a full-page story on the movement in 1992 calling them "one of the world's fastest-growing and most innovative bands of Bible thumpers" that had grown into "a global empire of 103 congregations from California to Cairo with total Sunday attendance of 50,000".

[12] By 2001, the ICOC was an independent worldwide movement that had grown from a small congregation to 125,000 members and had planted a church in nearly every country of the world in a period of twenty years.

[8][29] In his 2001 book The New Believers: A Survey of Sects, 'Cults' and Alternative Religions, David V. Barrett wrote that the ICOC was "currently causing perhaps more concern than almost any other" evangelical church in the United Kingdom.

After much counsel with the Gempels and Bairds and other World Sector Leaders as well as hours of prayer, we have decided it is God's will for us to take a sabbatical and to delegate, for a time, our day-to-day ministry responsibilities so that we can focus on our marriage and family.

Nearly a year later, in November 2002 he resigned from the office and personally apologized citing arrogance, anger and an over-focus on numerical goals as the source of his decision.

Sixty-four Elders, Evangelists and Teachers wrote a letter to McKean expressing concern that there had been "no repentance" from his publicly acknowledged leadership weaknesses.

The lawsuits alleged that members were forced to give 10% of their income as a tithe to the church and additionally to fund twice-yearly special mission trips, which drove some to depression and suicide.

Each regional family of churches sends Evangelists, Elders and Teachers to an annual leadership conference, where delegates meet to pray, plan and co-operate world evangelism.

In 2013, the MTA finalized a curriculum consisting of twelve core courses that are divided into three areas of study: biblical knowledge, spiritual development, and ministry leadership.

[60][better source needed] They believe that anyone who follows the plan of salvation as laid out in the scriptures is saved by the grace of God, through their faith in Jesus, at baptism.

[citation needed] The ICOC, like the Christian Church (Disciples of Christ), in contrast to the CoC, consider permissible practices that the New Testament does not expressly forbid.

[68]: 23, 24 [69][70] This belief dates to the beginning of the Restoration Movement; Thomas Campbell expressed an ideal of unity in his Declaration and address: "The church of Jesus Christ on earth is essentially, intentionally, and constitutionally one.

McKean's mentor, evangelist Chuck Lucas, developed this practice based in part on the book "The Master Plan of Evangelism" by Robert Coleman.

"[75] Under McKean, "discipling" entailed members being "assigned a more senior adviser who is always available and frequently present in their lives, even at intimate moments, which mentors them through relationship difficulties.

[76] According to Kathleen E. Jenkins's ethnography of the church, McKean viewed discipling as "the most efficient way to achieve the movement's stated goal: 'to evangelize the world in one generation'".

These intimate racially and ethnically diverse discipling networks provided members with social resources such as childcare, teen counseling, tutoring, employment opportunities, domestic help, and other kinds of assistance in day-to-day living".

[7] According to Joseph Yi, writing in 2009, with the departure of McKean in 2002 the ICOC transitioned from a top-down organization to a "loose federation of autonomous local churches".

[90] In response, a spokesperson for the New York Church of Christ stated that "This word 'cult' is so inflammatory and thrown around so loosely that it is completely unfair and totally unfounded".

[97] By 2000, according to US News & World Report, "[a]t least 39 institutions, including Harvard and Georgia State, [had] outlawed the organization at one time or another for violating rules" regarding recruiting and harassment.

[16][91] The ICOC's group at the University of New South Wales (where it is formally banned), the UNSW Lions, has repeatedly renamed itself to maintain a presence on campuses.

Jenkins also notes that "mandatory close and frequent social interaction forced members to develop such strong cross-racial and ethnic networks".

[7] Writing in 2004, Kevin S. Wells reported that "The fact that ICOC congregations are typically multicultural has [...] gained the positive attention of national media in recent years".

Nonetheless, by 2022 most congregations had begun conversations about "racial inclusion, diversity and justice", although Michael Burns states that "It seemed [...] that very few had undertaken to carefully examine their history, beliefs, practices, and systems and subsequently engaged in significant structural change".