(Answering the question, “What is the greatest thing God could create?”)
I’m not so sure I agree. First of all, God is not created, so any copy of Himself would, by definition, not be identical, because it would be a created thing. God is the source of all things. This other creature could not also be the source of all things, as it would not be the source of itself, much less God, nor would it be the source of everything else God had created.
Also, I don’t know that, assuming this other God-like creation had free will, that God could guarantee it would choose Good. God will always choose good because it is in his nature to do so; for this other creature to have free will, it must have the ability to define its own will, otherwise, again, it would not be identical to God. It would be a pretty horrible thing for the rest of creation if this God-like creature had the power of God but lacked His will and were to choose to act against it.
This would also raise a conundrum along the lines of “can God create a rock so heavy He can’t lift it,” because, if He is all powerful, there can’t be a rock so heavy He can’t lift it. If God is all-powerful, there cannot be a being that is so powerful He cannot overcome it, otherwise He would not be all-powerful. Similarly, if this other creature were all-powerful, it would be able to overcome God, but since God is all-powerful, that is impossible. You simply cannot have two all-powerful Gods.
But putting these issues aside, I don’t even know that being equal to God would necessarily be good for anyone but God. The Bible tells us that Jesus, “though he was in the form of God, did not regard equality with God something to be grasped.” (Philippians 2:6) As created beings, having the capacity to love that which created us and know that we are loved by Him is itself a great gift, especially when that which created us is the greatest Good, the source of all goodness. If we perceived ourselves as equal to that Creator and did not see ourselves as dependent upon it, we might not be capable of loving Him in the same way.
While I understand that there is perfect love between the Father, Son and Holy Spirit, all three of which are God, none of these three are creations of God, and the question is about the greatest thing God could
create. It seems to me that, as creations, the ability to love our Creator may be contingent upon our recognizing ourselves as creations, as something less than that which created us.
Full disclosure – I’m not a theologian and welcome correction if I have erred in expressing how this “might” work.