There are not objections about God “changing his mind”. Language in scripture can be metaphorical and figurative, just like in other literature.
1 Moreover, from the foregoing, consideration can be made of a twofold order: one depends on the first cause of all, and consequently takes in all things; while the other is particular, since it depends on a created cause and includes the things that are subject to it. The second is also of many types, depending on the diversity of causes that are found among creatures.
Yet, one order is included under another, just as one cause stands under another. Consequently, all particular orders are contained under the universal order, and they come down from that order which is present in things by virtue of their dependence on the first cause.
An illustration of this may be observed in the political area. As a matter of fact, all the members of a family, with one male head of the household, have a definite order to each other, depending on their being subject to him. Then, in turn, both this head of the family and all other fathers who belong to his state have a certain order in regard to each other, and to the governor of the state; and again, the latter, together with all other governors who belong in the kingdom, have an order in relation to the king.
Notes As it should be.
2 However, we can consider the universal order in two ways, in accord with which all things are ordered by divine providence: that is to say, in regard to the things subject to the order, and in regard to the plan of the order which depends on the principle of order.
Now, we showed in Book Two that these things which are subordinated to God do not come forth from Him, as from one who acts by natural necessity, or any other kind of necessity, but from His simple will, especially as regards the original establishment of things. The conclusion remains, then, that apart from the things that fall under the order of divine providence God can make other things, for His power is not tied down to these things.
3 But, if we were to consider the foregoing order in relation to the rational plan which depends on the principle, then God cannot do what is apart from that order. For that order derives, as we showed, from the knowledge and will of God, ordering all things to His goodness as an end.
Of course, it is not possible for God to do anything that is not willed by Him, since creatures do not come forth from Him by nature but by will, as has been shown. Nor, again, is it possible that something be done by Him which is not comprehended in His knowledge, since it is impossible for anything to be willed unless it be known. Nor, further, is it possible for Him to do anything in regard to creatures which is not ordered to His goodness as an end, since His goodness is the proper object of His will. In the same way, since God is utterly immutable, it is impossible for Him to will something which He has previously rejected with His will; or for Him to begin to know something new; or to order it to His goodness in a new way.
Therefore, God can do nothing that does not fall under the order of His providence, just as He can do nothing that is not subject to His operation. Nevertheless, if His power be considered without qualification, He can do other things than those which are subject to His providence or operation, but, because of the fact that He cannot be mutable, He cannot do things that have not been eternally under the order of His providence.
Notes It may help to recall that God is not in time as we are.
4 Now, certain people who have not kept this distinction in mind have fallen into various errors. Thus, some have tried to stretch the immutability of divine order to the things themselves that are subject to the order, asserting that all things must be as they are, with the result that some have said that God can do no things other than what He does. Against this view is what is found in Matthew (26:53): “Cannot I ask my Father, and He will give me more than twelve legions of angels?”
5 Certain others, conversely, have transferred the mutability of things subject to divine providence to a mutability of divine providence, thinking in their carnal wisdom that God, in the fashion of a carnal man, is mutable in His will. Against this it is stated in Numbers (23:19): “God is not as a man that He should lie, nor as the son of man that He should be changed.”
6 Others still have removed contingent events from divine providence. Against them it is said in Lamentations (3:37): “Who can command a thing to be done, when the Lord commands it not?”