The Gospel of the Christ teaches merciful love, while the Old Testament teaches a malevolent punitive justice. The Christ is the Son of a God of love and the faith in this God is the essence of Christianity. The history of the whole world, described in the Old Testament, from Adam to Christ, forms an immoral and repulsive drama, staged by a God who created this world, who is as bad as possible and who, consequently, cannot be better than his lamentable creation. Thus it is impossible that the Christ is the Son of the Creator revealed in the Old Testament. This creator is just and cruel, whereas Jesus is love and kindness personified. Therefore, Jesus is, by his own avowal, the Son of God. He thus can only be the Son of a God completely different from that of the Old Testament. He is the Son of a Good God, residing until now unknown to man and a stranger to this universe, because he had absolutely nothing in common with it. This God is the Unknown God that Saint Paul announced at the agora of Athens. The Christ is his Son.
The Old Testament lost its quality as the Holy Scriptures of Christianity. It did not know the True God and did not know anything about Jesus. The words of the prophets and the psalms, until then considered to be prophecies relative to the Christ, must now submit to a literal reinterpretation, after which they no longer apply to Jesus. The Law and the prophets ended with John the Baptist. John was the last Jewish prophet; like his predecessors, he preached a Demiurge of cruel justice, he knew nothing of the Good God, who remained foreign to all the Jews. That he was also good, Jesus himself confirmed it. He [Jesus] did not cease, in his language as well as in his conduct, to violate the Law of the Old Testament, to disobey the God who instituted it. He declared an open war on the Law, the scribes and the Pharisians. Jesus welcomed the sinners insofar as they had corrupted themselves with those who passed for just in the sense of the Old Testament. Jesus had seen in the last prophet of the Old Testament, John the Baptist, an ignoramus and an subject of scandal. John himself had said that the Son was the only one to know the Father and that, by consequence, all of those who had come before him had known nothing of him, but had preached another God [...]
When Jesus spoke of the bad tree that could only bear bad fruit and the good tree and its good fruit, he understood the bad tree to be the God of the Old Testament, which had only created and could only create what is bad. The good tree, on the other hand, is the Father of the Christ, who only produced good things. And, by defending the stitching of a new piece into an old frock and putting new wine into old bottles, Jesus expressly prohibited the establishment of any kind of connection between his Gospel and the religion of the Old Testament, with its God.
(Leisegang, H., La Gnose
, Paris, 1951, my bold)