1st, That if the will of God were not unchangeable, he could not be the object of trust; for how could we depend on his promises, were it possible for him to change his purpose? Neither would his threatenings be so much regarded, if there were any ground to expect, from the mutability of his nature, that he would not execute them; and by this means, all religion would be banished out of the world.
2dly, This would render the condition of the best men, in some respects, very uncomfortable; for they might be one day the object of his love, and the next, of his hatred, and those blessings which accompany salvation might be bestowed at one time, and taken away at another, which is directly contrary to scripture, which asserts, that the gifts and calling of God are without repentance, Rom. xi. 29.
3dly, None of those things that occasion a change in the purposes of men, can be applied to God; and therefore there is nothing in him, that in the least degree can lead him to change his will, or determination, with respect to the event of things. For,
1st, Men change their purpose, from a natural fickleness and inconstancy, as there is mutability in their very nature; but God being unchangeable in his nature, he must be so in his purpose or will.
2dly, Men change their purposes in promising, and not fulfilling their promise, or, as we say, in being worse than their word, oftentimes from the viciousness and depravity of their nature; but God is infinitely holy, and therefore, in this respect, cannot change.
3dly, Men change their mind or purposes, for want of power, to bring about what they designed; this has hindered many well concerted projects from taking effect in some, and many threatenings from being executed in others; but God’s will cannot be frustrated for want of power, to do what he designed, inasmuch as he is Almighty.
4thly, Men change their minds many times, for want of foresight; something unexpected occurs that renders it expedient for them to alter their purpose, which argues a defect of wisdom: but God is infinitely wise; therefore nothing unforeseen can intervene to induce him to change his purpose.
5thly, Men are sometimes obliged to change their purpose by the influence, threatenings, or other methods, used by some superior; but there is none equal, much less superior, to God; and consequently none can lay any obligation on him to change his purpose.
VII. God is incomprehensible: this implies that his perfections cannot be fully known by any creature; thus it is said, Canst thou by searching, find out God? Canst thou find out the Almighty unto perfection? Job xi. 7.
When we consider God as incomprehensible, we do not only mean that man in this imperfect state, cannot fully comprehend his glory; for it is but very little, comparatively, that we can comprehend of finite things, and we know much less of that which is infinite; but when we say that God is incomprehensible, we mean that the best of creatures, in the most perfect state, cannot fully conceive of, or describe his glory; and the reason is, because they are finite, and his perfections are infinite; and there is no proportion between an infinite God, and a finite mind: the water of the ocean might as well be contained in the hollow of the hand, or the dust of the earth weighed in a balance, as that the best of creatures should have a perfect and adequate idea of the divine perfections. In this case, we generally distinguish between apprehending, and comprehending; the former denotes our having some imperfect, or inadequate ideas of what surpasses our understanding; the latter, our knowing every thing that is contained in it, which is called our having an adequate idea thereof: now we apprehend something of the divine perfections, in proportion to the limits of our capacities, and our present state; but we cannot, nor ever shall, be able to comprehend the divine glory, since God is incomprehensible to every one but himself. Again, we farther distinguish between our having a full conviction that God hath those infinite perfections, which no creature can comprehend, and our being able fully to describe them: thus we firmly believe that God exists throughout all the changes of time, and yet that his duration is not measured thereby, or that he fills all places without being co-extended with matter; we apprehend, as having an undeniable demonstration thereof, that he does so, though we cannot comprehend how he does it.