The phrase was derived from the Bible verse, II Corinthians 6:17 which read "Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you.
In 1832, he printed an anti-slavery tract called Thoughts on African Colonization which included the "come out from among them" verse from the Second Epistle to the Corinthians, and a quote from a recently deceased Reverend Doctor Thomson of Edinburgh: "To say that we will only come out of the sin by degrees—that we will only forsake it slowly, and step by step... is to trample on the demands of moral obligation..."[3] At the New England Anti-Slavery Convention in 1836, Garrison proposed that only churches willing to help fight slavery should be considered "the true and real church of God.
"[4] This was viewed by many as too divisive, so other means were tried until the 1837 convention when a resolution was adopted urging abolitionists to leave unresponsive churches, "to come out from among them and be separate.
[7] Come-outers themselves split further into those who, like Garrison, were against any institution at all, and those who believed that political systems and churches could be reformed into anti-slavery organizations.
[8] The integrated American Missionary Association, a non-denominational group, formed in 1846 mostly of Presbyterian and Congregational members who were unable to get their churches to commit to fight slavery.