If you are "just tuning in" and are not familiar with this site, let me recommend you read POLITICS AND RELIGION: PART FIVE. Nothing I have written before it, and most likely, nothing I will ever write, will be as important to the reader. It is essential that one understands exactly what True Christianity is!
Although the ministry of Jesus occurred during the Dispensation of the Law, He was telling Nicodemus what is true for all seven dispensations: You must be born again (John 3:1-21). One is born of the Spirit by faith, and the Word clearly teaches that belief results in imputed righteousness (Genesis 15:6; Romans 4:3; Galatians 3:6; and James 2:23). Abraham did not have the light that the Church now has, but he believed the light he did have, and God covered him in the blood of Jesus who was crucified in God's economy before the world was made (Revelation 13:8). Abraham did not have a Bible. In fact, no one had a completed Bible until around A.D. 100. Nevertheless, when a man, from Adam all the way to the end of the Millennium, believes what God has revealed to him, he is counted as under the blood of Jesus. Faith comes when one recognizes what God says is truth. It is not something we decide to do, but something the Spirit does in us. Faith is a gift from God (Ephesians 2:8-9). We simply believe.
Unfortunately, the Church has had problems with people adding and taking away from the simple Gospel. Paul confronted the Galatians in the first century (1:6-9). Throughout his ministry, Paul was constantly under attack by those who demanded converts become Jews first. Even after the council that declared this not to be true (Act 15:1-27), there was still opposition.
Another problem the early Church faced was that of division (Romans 16:17; 1 Corinthians 1:10; 3:3; 11:18). And although Jesus clearly wanted the Church to be united (John 17:11; 21-13), it appears that it never has been. For the first three centuries, the Church struggled with establishing itself in the face of severe persecution. Once Rome merged politics and religion by making Christianity the official religion of the empire, corruption of doctrine abounded. When the Empire fell, the Church continued to be a combination of politics and religion in the form of the Roman Church, which slaughtered anyone who failed to acknowledge its teachings as equal to the Bible. In A.D. 1054, the Catholic (Universal) Church split into the Eastern and Western divisions. This lasted until the Reformation which split the Church several times over with denominations beginning in the early 1500's. Today, who knows how many divisions there are.
Division results from a failure to compromise concerning one's beliefs. God has used the increased understanding of His Word to spread the Gospel, just as He used the confusion of tongues to correct those building the Tower of Babel. So, was Jesus wrong to desire that the Church be one? I will try to answer that tomorrow, Lord willing. Keep looking up for your redemption draweth nigh.