Charnock on God's Omniscience

If God did not know all future things, he would be mutable in His knowledge. If He did not know all things that ever were or are to be, there would be upon the appearance of every new object and addition of light to His understanding and therefore such as change in Him as every new knowledge causes in the mind of a man or as the sun works in the world upon its rising every morning, scattering the darkness that was upon the face of the earth.

If He did not know them before they came, he would gain a knowledge by them when they came to pass which He had not before they were effected; His knowledge would be new according to the newness of the objects and multiplied according to the multitude of the objects.

If God did know things to come as perfectly as he knew things present and past, but knew those certainly and the others doubtfully and conjecturally, He would suffer some change and acquire some perfection in His knowledge when those future things should case to be future and become present; for He would know it more perfectly when it were present that He did when it was future, and so there would be a change from imperfection to a perfection.

But God is every way immutable.

— Stephen Charnock

Discourses upon the Existence and Attributes of God, 279

Ore from the Puritans’ Mine, 212-13