First you say that God exists entirely outside of time, then you say that God entered time. Which is it?
A metaphor that has allowed me to visualize this nature of God may help.
Suppose we have a two dimensional drawing on a piece of paper, which we have created. We then imbue our drawings with sentient life. Now, we are not present in and constrained by the two dimensions of our creation. However, at any moment, we may put pencil to paper and add to or take away from the drawing. Our two dimensional drawing of Tomdstone may then argue that if these changes were the result of our creators, they must be contained by the two dimensions of his observable reality; if the creators are outside of those dimensions, then they can’t affect them. However, from our ‘higher’ position in reality, we can see that isn’t true.
Of course, this is an imperfect metaphor, as are all attempts to communicate divine realities. We can see how difficult it would be to communicate a third spatial reality to our two dimensional creatures. The very words we would need to do so would have no meaning to them. So we would have to use left/right and up/down to communicate the concept of depth. How much more difficult for finite beings such as ourselves to comprehend an infinite, perfect being? Infinitely more difficult.
You see passages that speak of God being angry or changing His mind, and read them as a finite creature who is imposing his perception of time and finite space on an infinite being. It just isn’t going to work. All this language is the best means we have to approach the meaning of God and His actions. He is outside of, beyond, and surpasses creation; there is no logical contradiction, such that you are attempting to demonstrate, in God affecting creation. It is His infinite pen to the paper of creation.