Denominationalism can be defined as religious division caused by false teaching, so the case could be made that its origin traces back to the beginning of creation, with the account of Cain and Abel. Abel followed correct doctrine with his sacrifice, as God ‘respected’ it, whereas Cain chose to alter whatever instructions God had issued on the subject, choosing instead a different doctrine or ‘denomination', and offering a sacrifice which God did not ‘respect’, one in which God had not ordained. (Genesis 4:3-5) Most denominations today attempt to follow some things taught or practiced by Jesus and His apostles. But these have been added to or modified to fit human ideas. We see this practice exhibited, even in the Old Testament. Israel “feared the Lord” (seemingly giving God some worship), yet they also served other gods, according to the nations around them (2 Kings 17:32-33). Mixing truth with non-truth makes discernment of God’s desired worship much more difficult, and “worshipping in vain” much more of a danger. (Matthew 15:9). The author explores denominationalism in this series, examining a number of the more popular main-line denominations to simply compare each with the Scriptures and to Christ’s church, as He established in the first century - in areas of Origin, Organization, Authority, Belief, Doctrine, and Worship Protocol. It is hoped that by doing so, some light will be shed on what appears to be a very gray area for many on this subject.