Moral life is a different thing from mere physical or instinctive life. There is a sense in which God is the life of everything. He is the life of the earth, the sky, the waters. He is the living principle of whatever the earth produces, — of the leaf, the flower, the plant, the tree. He is the life also, by means of their various and wonderful instincts, of all lower animals. But he is their life, in some cases, without their knowing it at all, because they are not percipient existences; and in other cases, without their exhibiting any distinct recognition and knowledge, if it is possible that they have It. But it is not so with moral beings. God is and can be the life of such beings, only so far as he is so with their own consent. In the words of a modern English poet,
"Our wills are ours; we know not how;
Our wills are ours, to make them thine."
So that it is not more necessary that God should be our life, than it is that we should choose him to be so. If it be true that we cannot live without the life of God in the soul, it is also true that we cannot have that life without our own choice. And the reason is, that the principles of moral government, as it exists among beings who are subject to the supremacy of a divine government, require, without the exclusion of either, that there should be an harmonious action and union of the two in one. When God works within us with our own consent and in answer to our own prayer, then the human and divine may be said to be reconciled, because the work of God, by the harmonious adjustment of the two, becomes both the work of God and the work of the creature. So that it is true, in all cases of holiness actually experienced that the man lives and has a true life; while it is also true, and in a still higher sense, that God lives in him.
— edited from A Treatise on Divine Union (1851) Part 7, Chapter 10.