If God is eternal then he does not change, since what is eternal is not subject to time.
So how can a changless God produce changes in a constantly changing world?
The same way an author not subject to the time in his book can write the book?
Because part of the definition of ‘God’ will conveniently include ‘can do whatever the heck he likes, even if this doesn’t seem to be possible or make strict logical sense in our universe’
God laid out the Cosmic Plan; all change has already been determined in advance 
Change does not necessarily depend on temporality; if it did, then theories about an eternal universe would be ridiculous. (They are anyway, but not for that reason.) There are dozens of definitions of time, and only one of them is the irreversible entropy arrow. Your premise is rather like saying that a three-dimensional creature is incapable of making an appearance in a two-dimensional world since he is not subject to height. The limitation in fact is not on the creature, but on the perception of the two-dimensional world.
Which reason, then?
I agree that a universe which has existed for an infinite amount of time is absurd given that the stars still shine, but a universe which is eternal, ie. exists for all time? Ridiculous how?
liberal:
I disagree - a precondition of movement (change) is space-time. If you are suggesting that change exists outside of space-time, then you are talking about a different kind of change and i’d be interested to know more about what you mean.
As for your analogy if a 3D being made an appearance in a 2D world, then it would be a different being. Hence it is incapable of making an appearance.
I always assumed that “God is eternal” means “God has always existed”. It’s not a statement about God being static or dynamic.
Christians would, I think, have to say that God “changes” – He became human and died and was resurrected, according to Christianity, and that’s surely “change”.
But if God exists, then He exists outside of space-time as we know it. Laws of physics don’t apply to a Creator Spirit, that’s the Spirit that creates the laws of physics.
Yes, CK but such an act of creation involves a change from one state to another.
If as you are saying there is a God, and that God does things - then he is an agent of change. If he is an agent of change, then he is at least subject to time: you have a sequential transition between states - a before and an after. Its that old chestnut of a paradox to say that he created time - it implies time has a beginning and hence a “before time was created” which is false.
Just because God can effect a change in the universe does not mean that God has changed. It’s the state of the universe that has transitioned, not necessarily the state of God. Christ’s coming and going is a change in humanity’s relationship with God, but doesn’t require that God has changed.
If God is outside the space-time of our universe, it is meaningless to talk about God changing or not changing. There’s no reference frame for a description.