I think that the richness and complexity of God, and His Truth, are not what divides us. For God's children, I would say these are the things that unify us!
God has called us to unity, and to maturity. Unity in the Truth, the one Truth of the Father, and it takes maturity to be able to digest this Truth. We apply ourselves in study, yes, but this is purely a tool the Holy Spirit uses. God made work, and we should work hard at study and application of His Word...we should be feeding on it. God has chosen the plain teaching of the Cross, and Christ Crucified, to reveal His rich and complex Wisdom to man, though. Why? So that we glory only in the Lord, and not in the teaching of man. We can not receive greater Truth, or meat, in our own wisdom (which divides). We can not receive it unless we mature to a point that milk no longer sustains. Even children, and the simple minded, can grow in the simple Truth and grace of the Father's Doctrine just by applying it in Holy Fear.
Remember, Jesus prayed that we would have unity, and we are exhorted by the Word to walk in the Truth. These two things are not at odds for the sincere believer. The divison comes in when there are motives that need to be revealed, and false motives can not stand agains Truth...it is a filter of sorts for those who are not walking in the Spirit and in Truth. We need them to be rooted out so that deception can be dealt with, and not allowed to run rampant, especially for the sake of those on milk. We have to be careful not to offend these little ones, and I think that is why God warns that teachers will be held accountable for what they teach.
The Father's doctrine is simple, to love God with all, and to love one another as we love ourselves. Simple, but so very difficult to live when we use man's wisdom, but not if we apply God's Truth! How will they know us? By our brotherly love! So, in the course of our walk, in our tribulations, and so on we grow, and produce fruit, and the love of God is shed across our hearts. This brings us to maturity, to meat, and to the ability to carry out such a simple doctrine, and to be unified in His Truth alone. In our maturity we become more focused on just obeying God, and do not get stuck on the how or why of those fundamental things that we should already know. We can teach it only when we live it, and example it. One of the problems we have are teachers who are on milk, and puffed up in their own wisdom, and lacking a mature walk in Christ.
When we lack maturity, and Truth, we divide. We are not filled on the living Word, but feeding on man's 'dead food'. When we do this, God gives us over to our own devices...and He allows us to walk in our own counsel. Consider this verse...
Psalm 81
10 I am the LORD thy God, which brought thee out of the land of Egypt: open thy mouth wide, and I will fill it.
11 But my people would not hearken to my voice; and Israel would none of me.
12 So I gave them up unto their own hearts' lust: and they walked in their own counsels.
Denominations are our downfall, they are our pride, and our own counsel. We have been given over to them much like Israel. The answer isn't the Baptist Church, or the Methodist, or the Catholic, it's Jesus, His Word, and the Wisdom of God imparted by the Holy Spirit for the mature believer. We have taken on His name, haven't we? Jeremiah 15:16 Thy words were found, and I did eat them; and thy word was unto me the joy and rejoicing of mine heart: for I am called by thy name, O LORD God of hosts.
Just some more thoughts (In the midst of the present chaos of the children dancing and singing Gospel bluegrass here in our house! Yes, I said bluegrass!). The Lord bless all of you.