"Why all this petty bickering? We all worship the same God, we just differ on the details. Does it really matter? Stop arguing, and unite!" Does that sound familiar?
It has been said that the Christian worships the same God as the Muslim and just about anyone else, and we shouldn't worry about the particulars. Why should anyone care about the Trinity and if Jesus Christ is God? After all, you can follow His teachings without believing He is the Creator of all things.
I want to point out why it matters, and the first reason is because He said it did! It wasn't some nit-picking theologian who said that failing to believe in the true identity of Christ meant damnation - it was Christ Himself who said, "If ye believe not that I am He, ye shall die in your sins" (John 8 v 24), and later in that very chapter He let them know unmistakably who He was claiming to be (John 8 v 58-59) - none less than God. John, the apostle, also claimed that belief in the true identity of Christ was vital for salvation. He said, "Every spirit that confesseth not that Jesus Christ is come in the flesh is not of God..." (1John 4 v 3). When we put these statements together we see that someone cannot be rescued from their sin while denying the true deity and humanity of the Lord Jesus Christ.
The reason our faith needs to rest on a fully divine, truly human Saviour is because a Saviour who is not really divine or not really human is actually no Saviour at all. If the Lord had not been God then He could not have paid the penalty for sin - only one who is infinite could exhaust infinite wrath and pay that infinite price. If the Lord had not been human then He could not have paid the penalty for sin because He had to suffer and die, which He could not have done apart from a real incarnation into humanity.
Paul warned about those who would preach "another Jesus" (2Corinthians 11 v 3-4). There's only one Jesus who can save sinners, it is the one who was eternally God who became flesh and dwelt among us (John 1 v 1, 14). If you have your faith in any other person you have your faith placed in one who cannot save. That's why it matters.
