My favorite book in the Bible is John’s gospel account. He stated his purpose clearly:

Many other signs therefore Jesus also performed in the presence of the disciples, which are not written in this book; but these have been written that you may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name. (Jn 20:30-31)

There are many details in this gospel that are not found in the Synoptic Gospels, and, conversely, he does not repeat what they recorded. Dr. Stanley Ellisen, in his Bible Outline Series, noted:

Note his avoidance of nouns such as “knowledge,” “wisdom,” and “faith” (abstractions much used by the Gnostics) while stressing the verb forms as “believe.” (see)

The question, who was Jesus? was paramount due to the encroachment of the Cerinthian Gnostics, who denied the deity of Christ Jesus. This heresy is still prevalent today. While there are many ways in which John profoundly rebutted the errors, one of the strongest is Jesus’ repeated use of the phrase “I am” (Greek ego eimi), thereby identifying Himself as the God of Israel, as He did to Moses at the Burning Bush. (cf. Ex 3:14)

In the phrase ego eimi, ego is an emphatic first-person pronoun followed by the verb eimi (Present Active Indicative). The phrase occurs twice in Matthew and three times in both Mark and Luke, but fourteen times in John’s gospel account. Seven times as an absolute declaration, i.e., simply “I am,” and seven times with a predicate nominative. For example, “I am the bread of life,” “I am the light of the world,” “I am the door,” “I am the good shepherd.” Each time, Jesus was identifying Himself as the Son of God, the same God who commissioned Moses to lead Israel from bondage in Egypt to the Promised Land.

Jesus’ identification of Himself as the Great I Am was not lost on the Jews. In John 8:58-59, when Jesus identified Himself as the “I am” Who existed before Abraham, they attempted to stone Him to death.

When witnessing concerning our faith in Christ Jesus, we need to be armed with a coherent understanding of John’s gospel account. Both his style and content were prepared and preserved by God for this very purpose. Dr. Ellisen’s extensive outline is a good place to start for anyone who questions the Hypostatic Union of the Second Person of the Godhead, i.e., Absolute Deity, Perfect Humanity, united in one Person forever.

The historical facts of Jesus’ existence have never been successfully challenged. John’s authorship was not challenged until recently (see). Careful attention to detail in his gospel account underscores its veracity. His style and composition provide details that each one of us needs to recall in order that we:

…may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name.  (Jn 20:30-31)