Why Denominations?

Because people are different! We’re all at different places in our faith, our understanding, and our willingness to accept certain rules, manners, and customs. We tend to hang with the flock that we’re most comfortable with at the time. Our Father loves all of His children, wherever they may gather. He is always leading them toward unity in the faith, but this doesn’t mean that any of us are there yet. Some seem to think that they have an exclusive insight, seeing a part of God and the Kingdom that others don’t see. This might just be true! How? God shows Himself in different ways at different times to different people. He is ever consistent, but our individual understanding and growth are not.
We can be stubborn, basing our understanding on personal experience and observation rather than the plain reading of scripture. We’ve never seen this interpretation or that doctrine practiced, so we doubt it’s real, or that the Bible can or should be used that way. Other times we are just lazy and passive, enjoying the nest and not ready to fly anywhere else. On the other hand, we may be eager to learn and grow, to hear what God says and to do it wholeheartedly. In any case, we tend to hang out with those who have the same attitude as we do. It’s not necessarily evil, it’s just human. There’s a reason why Jesus compares us to sheep!
(Matthew 18:20, Psalms 25:14, Ephesians 3:5, Luke 4:25-27, Isaiah 40:11, Ephesians 4:11-13, Philippians 3:12-14)