Rapid growth was experienced in its initial decades, and Irvine eventually came into conflict with the regional overseers whom he had appointed to administer the now worldwide religion.

[2] For convenience, William Irvine's career as an evangelist may be divided into 3 periods, though they would have been seen as a continuous stream with considerable overlap during those years.

John Long describes Irvine as "In either secular or religious matters, he was a born leader of men; he was a holy man, and practical.

[7][5] Irvine quickly became dissatisfied with the Faith Mission's rules, disciplines, teachings, growing organization and tolerance of churches.

In August 1897, Irvine and John Long held meetings independent of Faith Mission, in Nenagh, County Tipperary, Ireland.

Irvine abhorred the ways in which he perceived that various churches made distinctions between the rich and the poor, and this became a frequent subject of his sermons.

[15][14] He wanted to get back to biblical basics and taught that all true ministers must follow Jesus' instructions to the apostles in Matthew 10; leaving their homes, families, property and responsibilities and going out to preach two-by-two.

To a great degree, he copied the Faith Mission's methods and traditions; adopted their terminology; used their appearance standards for women evangelists; and appropriated many of their hymns.

Although he had ceased preaching inside the Faith Mission framework or reporting to its headquarters for some time, Irvine himself formally resigned from that organization only in 1901.

Edward Cooney also joined in 1901, selling all and donating the considerable sum of £1,300 to Irvine (a working family could live comfortably on an annual income of £57–78 during this time).

Irvine travelled widely during this period, attending conventions and preaching worldwide, and began sending forth workers from the British Isles to follow up and expand these footholds.

A controversial teaching, presumably originating with Irvine, was that of the Living Witness Doctrine (first recorded mention in a convention sermon by Joseph Kerr in 1905, which he later recanted after leaving the group).

As his message turned towards themes of a new era which held no place for the ministry and hierarchy which had rapidly grown up around the "Alpha Gospel," resentments on the part of several Overseers came to a head.

These overseers rebelled against what they saw as Irvine's increasingly autocratic leadership in 1914,[32] and they refused to give him opportunity to speak at conventions held within their respective geographic regions.

Few were aware of the circumstances of his departure, and no public discussion of the matter seems to have occurred, although rumors of a "mental breakdown" or "indiscretions with women" were spread (the latter may have arisen out of his having fathered a son out of wedlock as a young man prior to his start in ministry).

Unlike those who continued to follow only his "Alpha Gospel", these refused to adopt any official name, although they came to be known among themselves as the "Message People" or "The Witnesses".

[44] As part of that role, he would eventually become one of (along with the Apostle John) the Two witnesses of Revelation ch.11 who would have special powers to prophesy and perform miracles, and would be killed in Jerusalem and raised up after 3½ days and taken up to heaven in a cloud prior to the return of Christ.

[45] He prophesied that there would be a coming great famine, and encouraged his followers to sell their homes and farms and invest their money in food and other provisions that would enable them to survive this impending calamity.

[48] The precise location within the cemetery was unknown for many years, as any marker was obliterated when the area became a no-man's land between Jordan and Israel between 1948 and 1967.

[49][50] It is not completely clear how followers of Irvine's "Omega Message" rationalised the facts of his death with the roles which he seems to play in his prophecies.