Denominationalism is the division of one religion into many separate groups, sects, schools of thought or denominations.Iron Curtain symbolized the ideological fighting and physical boundary dividing   a group of people though they share a common bond but are separate by ideologies. The Day that men like Constantine took the word of God and decided to change it for their purpose is when a great divide begain.
This may sound shocking to many but the concept of denominationalism which is many different denominations, teaching many different doctrines is not taught or sanctioned in the New Testament. Christ promised and did build "one body" or one church (Matt. 16: 18), (Eph. 1: 22, 23),  (Eph. 4: 4). The concept of many different denominations was absent in the First Century. Paul, therefore, taught "every where in every church" (I Cor. 4: 17). Denominationalism is division personified. The closest that we can come to denominationalism in the New Testament is the divided state of the church at Corinth. Paul did not praise this fragmented condition, but rather he condemned it. Observe Paul's inspired teaching:  "¹I appeal to you, brothers, in the name of our Lord Jesus Christ, that all of you agree with one another so that there may be no divisions among you and that you may be perfectly united in mind and thought. ¹My brothers, some from Chloe's household have informed me that there are quarrels among you ." (1Corinthians 1:10-11)