Wouldn’t it be great if that could happen! Well the truth of the matter is that it does and it doesn’t - let me explain.
The heart of the problem is sin. While Christians have been forgiven for their sin, sin will remain an ever present part of our lives until God has finally judged the world and taken his people to live with him. We can see the expression of that sin in the divisions and broken relationships we experience today between people, nations, races and even churches.
Part of the problem is defining what is the “core” belief of Christianity. If you were to ask different Christians you are likely to get some very different answers. For a traditional Catholic Christianity is following Jesus Christ by listening to the church and Jesus’ representative, the Pope. For Protestants it is following Jesus through reading his Word. For others, the authority that guides their belief is the experience of God and his Spirit. In the end it comes down to what a person uses as the authority of beliefs. Broadly speaking, people tend to choose one of four main authorities when it comes to understanding God; tradition (Church structures, practices and customs), revelation (the Bible), experience (personal spiritual experiences) and human reason.
The question is which one is right? For a traditional Catholic, the tradition of the church rates highly as the authority of their belief but for an evangelical the bible is the most important thing. So if the Catholic church tradition and the evangelical understanding of the bible differ, who should change? Or if the liberal Christian (who uses reason as the means by which to determine what is right and what is wrong) believes that miracles do not happen but the evangelical believes they do then who should back down? Historically these differences have led to churches splitting and creating new denominations based a their particular views and so we have the mishmash of denominations that we have. This is what I would call institutional disunity.
Now you may say why can’t we just forget these differences and just get along?
The problem is that some of these differences are not merely side issues that can be put aside like that but do come down to the very core of Christian belief. Questions like, ‘How do I find out about God?’ will be answered differently depending on which authority is used and for such defining questions you can;t have several contradictory answers either one person is right and the others wrong or all of them are wrong. In situations like this you would hope that the institutions could work it out but they don’t. Sin and pride get in teh way and the institutions continue to disagree at this fundamental level.
But there is a more fundamental unity that does exist amongst believers that transcends the institutions and is founded on faith in Jesus Christ. If Christianity is to be true to itself, it needs to be founded on Jesus Christ and his teachings, which is found in the Bible, particularly in the New Testament. The New Testament does hold out the ideal that Christians will be unified (Eph 4:3) but it is a spiritual unity based on Christ and expressed amongst individuals and not in human institutions. One challenge to unity is false teaching, which is one of the major themes of the New Testament (Acts 20:29; Mark 13:22; 2Cor 11:13,26; Gal 2:4; Col 2:18; 1 Ti 1:3, 6:3; 2 Pe 2:1; 1Jn 4:1; Rev 2:2). Given that false teaching is such a part of the reality of the early church, Christians have no expectation of eradicating it without a supernatural work of God. Like all sin forgiveness and healing from God are the only solution we have to this problem.
To see an end to the divisions Christians need to see that God is bringing all things toward unity in His Son. Christianity is at its heart a grass-roots movement of believers following Jesus Christ rather than an institutional system of religion. The answer to the divisions in the churches today is not ignoring the differences but discovering the unity than can be found in following Jesus together. Unity is not found in the diversity of church practices but in the core belief of following Jesus Christ (Rom 15:5). Unity in Jesus Christ is also the position of mature Christians (Eph 4:1-15). This is not an institutional unity, but a deep unity of faith and knowledge of God which transcends denominations, backgrounds cultures and ages.