Amos 3:3 asks the question, “Can two walk together , except they be agreed?” That text is sometimes interpreted to mean that if we disagree in any way, we must separate. The passage does not teach that. Study the context of the passage and you will see that God was dealing with the apostasy of Israel and not with denominational distinctives or minor disagreements. There is a proper ecumenism of separatist brethren as well as a false ecumenism of Satan’s system.
Separation is God’s answer to apostasy. Separation is God’s answer to the problem of disobedient brethren who will not separate from apostasy. But, separation is not the answer to every disagreement between brethren.
John Ashbrook in Axioms of Separation, p. 22.