"Christianity," -> Christian = follower of Christ and as I said the likes of, most of what you call - Christianity, - follow another Jesus = tradition of men and not according to Jesus.
So that, I do Not ascribe to, but the REAL Christ and I take notice of his recorded words;
This Now is the eternal life that they should know You (Father) the only true God and who you have sent, Jesus Christ = The Real one So, he clearly and independently of himself, defines the Father as the only true God when he was here.
(They are known as - The Word and The Word of God). Word God -> image of -> Word Man.
He also quotes from the OT in support of it -> Hear, Israel: Yehowah our God is ONE Yehowah = like one apple, singular -> The One Holy Spirit.