Sorry Mosher, you are hoist with your own petard.
If evil is just lack of good, then lying is not evil, it is just an omission to be good, therefore, if GOD lies, then GOD is not doing evil, merely abstaining from good.
The error is not mine, it is yours.
It is indeed this attempt to define inabilities of GOD that made the concept of gnosticism inevitable. The gnostics were merely trying to comply with these futile attempts to limit the capabilities of the ALMIGHTY.
I agree with Mosher who is following Augustinian thought. Evil is not a thing, it has no substance. It’s effects can have substance and can attach to a thing, but evil itself is not an entity, it has no substance and is defined really as an absence of God or an absence of good, or an absence of holiness. This is what evil is- a void.
Lying IS an omission of good because God gave us free will. When confronted with the opportunity to tell the truth or lie, and we lie, then we are not exercising our capacity for good, in fact we are doing no good, our direct immediate action is void of good. This is what sin is, and incidentally addressing you rpost further down, is why God cannot sin. God can never be devoid of good.
God cannot lie because we have a Trinitarian God. We have God the Father, God the Son and God the Holy Spirit. The word was with God in the beginning and we know that the Word was God because John tells us so. We know that God cannot deny Himself because Christ tells us so. In the Gospel. Christ gives a long homily on the denial of himself. He cannot do it he tells us.
He can deny us, we can deny Him as Peter did, but Christ/God cannot deny Himself. Now that is Gospel, Voco.
If God could either through His word, deny Himself, the Trinity would be less than perfect, therefore not all powerful. If you put forth that God as Word can lie, then the Trinity is imperfect and God is not All powerful. If you put forth that God can sin, then the Trinity is imperfect and God is not all powerful. And yet, Voco, you are saying that God can sin. God can lie. And trying to use the poor gnostics as evidence. This was not their game. The fact is once you claim that God can operate outside of good, or with an absence of good, or in defiance of good, then the three persons of the Trinity, Father Son and Spirit are no longer pure goodness and all goodness and the source of all goodness and mroe than that they are no longer
perfectly good for now there is a void in tht goodness due to whatever action you have assigned, sin or lying, and therefore are no longer perfect and absolutely not all powerful.
Now Aphrodite, and Persephone and Zeus and all the other gods could lie and play dialing for dollars for human fates. They could stay in their respective heavens untouched and tell a lie or sin in order to direct human affairs much like kids playing with dolls in a doll house. And the Greeks and Romans accepted their gods as all powerful.But they wre fatalists.
You see when you start putting forth that your Trinity is capable of lying, or sinning or committing an evil act, you have set out on the journey toward fatalism. We are not fatalistic people. Primarily because we have a God who is all Powerful because he is perfect and all good.