In the Old Testament the New is concealed, in the New Testament the Old is revealed.
Augustine of Hippo
I beg every devout Christian not to despise the simplicity of language and the stories found in the Old Testament. He should remember that, however simple the Old Testament may seem, it contains the words, works, judgments and actions of God himself. Indeed the simplicity makes fools of the wise and clever, and allows the poor and simple to see the ways of God. Therefore submit your thoughts and feelings to the stories you read, and let yourself be carried like a child to God.
Martin Luther
The Old Testament does not occupy itself with how Israel thought of God. Its concern is with how Israel ought to think of God. The fundamental note of the Old Testament is revelation.
Benjamin B. Warfield