Marcion and Luke
The New Testament did not establish the Christian church but the Christian church established the New Testament.
However, it is not the Christian church that is important and essential in Christianity but it is the teaching of Christ Jesus. And it was not His own will and plan that God's will and plan that made Christ Jesus preach to people.
Put simply, God used Christ Jesus, the Christian church, and the Bible. So, if you concentrate on God directly, you may be allowed to neglect the Bible, the Christian church, and even Christ Jesus. But if you deal directly God, you must be careful. There is an example of Marcion:
Marcion of Sinope (c. 85 – c. 160) was an important figure in early Christianity. His theology rejected the deity described in the Hebrew Scriptures and in distinction affirmed the Father of Christ as the true God. The Church Fathers denounced Marcion, and he was excommunicated from the proto-orthodox church. He published his own list of New Testament books,[3] editing some (the Gospel of Luke) and rejecting other books of the New Testament making him a catalyst in speeding up the process of development of the New Testament canon by forcing the early Church to respond to his claims.However, it looks reasonable to judge that God in the Old Testament is different from God in the New Testament. Such a feeling is beyond any arguments in theology, but if Christ Jesus had said that His God was different from the God of Jewish priests of the Jerusalem Temple who tried to kill Him, every follower of Christ Jesus must have been highly confused.
https://en.wikipedia.org/wiki/Marcion_of_Sinope
But it must be still studied how God of the Old Testament became the God of the New Testament, since the mankind has no ability to fully understand God and God is almighty. And it must be also studied why Marcion who thought the God of the New Testament was different from the God of the Old Testament chose only one Gospel among many: Luke.
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Mat 9:15 And Jesus said unto them, Can the children of the bridechamber mourn, as long as the bridegroom is with them? but the days will come, when the bridegroom shall be taken from them, and then shall they fast.
Mat 9:16 No man putteth a piece of new cloth unto an old garment, for that which is put in to fill it up taketh from the garment, and the rent is made worse.