Good question, Adopted Admiral. In the book," What People Ask About The Church," by Dale A Robbins, he poses the question, Why are there so many different churches? In answer to that question he points out several things that were helpful to me and I hope that will be helpful to you.
Regardless, of how closely various churches may agree with each other doctrinally, there will never be two churches exactly alike. This is largely due to the fact that there are no two people exactly alike. Churches are made up of people. The combined individual personalities in a congregation, creates a distinct "congregational personality." Sometimes people mistake differences in church personality as differences in belief or doctrine. A denomination is a cluster of separate congregations, which due to their agreement or disagreement with viewpoints of other churches, have unified together. According to Church Historian, Dr Bruce E. Shelley, the original usage of the term "denomination," actually stood for unity, not division. It was used to describe cooperation with other churches without compromise of fundamental convictions.
Denominations probably were not Christ's first choice for His church.
John 17:20-21 NIV "My prayer is not for them alone. I pray also for those who will believe in me through their message, that all of them may be one, Father, just as you are in me and I am in you. May they also be in us so that the world may believe that you have sent me."
But denominations came to help serve the purpose of God in many important ways; they helped to divide and scatter the influence of the Gospel to a wide spectrum of people, helped to filter out the spread of harmful heresies and false doctrines, and have unified significant portions of the body of Christ. Wise denominational leaders have used their influence to help their flock see the larger family picture of Christianity.
There's really only one true church-every church which is based on Jesus Christ as Lord and Savior is part of the true church.