In the book of Revelation, there is a message given to seven churches. If we accept this as a chronological statement of church ages from the early church to the church prior to the Second Advent, we learn how Christians could have walked in unity, but did not.
‘I know your works, your toil and your patient endurance, and how you cannot bear evil men but have tested those who call themselves apostles but are not, and found them to be false; I know you are enduring patiently and bearing up for my name’s sake, and you have not grown weary. But I have this against you, that you have abandoned the love you had at first. (Revelation 2:2–4)
The reason the church became the institution that was known as the Catholic Church (and later the Roman Catholic Church and Orthodox Churches) appears to be because those who professed a belief in Lord Jesus Christ fell away from pursuing a relationship with the Savior that was birthed by the Spirit of God and founded in the truth of experiencing the Divine (John 4:24). When people depart from the truth for personal ambition, there will always be schisms, because of idolatry, sorcery, enmity, strife, jealousy, anger, selfishness, dissension, party spirit (Galatians 5:20).
The True Church Is Not Of This World For The Kingdom Of God Exists In Our Spirit