Why not the Old Testament? God is constantly unhappy with the Jews throughout it.
I read somewhere that the difference between Allah and Yahweh is that Allah instructs his followers to commit the atrocities that Yahweh reserved for himself.
Exactly, and he refers to them in many ways because they are stiff necked and keep thinking they are the only ones God will favor. Even in the NT it refers to the only covenant between God and a faith but it is NOT a get out of jail free card, Gentiles are grafted into the “olive tree” and branches that do not produce fruit are cut off. Since they do not accept the payment for the sins by Faith in his son Jesus they are then judged by their works, hence the number of 144,000 of that faith that will be saved.