The law of identity and the law of the excluded middle
Would a rose by any other name smell as sweet? It may, but it wouldn’t be a rose. The law of the excluded middle and the law of identity need to be studied when dealing with Christianity. A rose is a rose, a rose can never be anything else. When it is named something else its identity is changed. A rose is always fully a rose. A rose is never almost a rose, or part rose and part something else. Same way with Christianity. A Christian is always a Christian, the definition of which in found in the Bible, Once you name “Christian” by any other name or change even one small aspect of the definition of “Christian” what you have is no longer a Christian. It is something else entirely.
This is why it can be said of denominationalism, “If one is called by Baptist, Methodist, Lutheran, Mormon, and others then one cannot be a Christian.” Incidentally, one who is a Baptist would never claim that if one were to follow part Baptist doctrine and part Methodist doctrine that one would still be able to be identified as Baptist or Methodist, they would have to be identified as something else entirely. As it relates to Christianity one would be part adherent to Christ’s doctrine and part adherent to manmade doctrine thus having an identity separate, different, and not aligned with Christ. He would no longer be Christian nor an adherent to Christianity.
To illustrate the aforementioned two laws notice the identity of animals who are the progeny of two different species. A male lion and a female tiger does not produce a half lion and a half tiger, the progeny of such unions are identified totally different from the parents, and rightly so, as liger. The progeny of a male donkey (jack) and a female horse (mare) is not half donkey and half horse, it is a mule, which is a totally different animal altogether from either of the parents. There are several other examples of the hybrid in the animal world.
The only way for a Christian to be produced is to be the progeny of God. We are born again by the Spirit (John 3:5). We are made partakers of his nature (2 Pet. 1:4). We are made sons and daughters through adoption (Eph 1:5). We are named by God (Isa 62:2; Acts 11:26). If we add anything to the doctrine of Christ we are no longer Christian. We are something else entirely and therefore have no place in Christ in whom are all spiritual blessings (Eph. 1:3).