Strawman and projection of your unbelief.
If the truth and reality are the result of God's believing mind and unbelievers disbelieve in God's truth occurring and reality's existence, then how can God know about a unbeliever's existence; when a believing mind is necessary in order to make the truth and reality known to begin with? If a unbeliever chooses to disbelieve in God's reality, then what is in a unbeliever that can be known to exist or occur in reality?
Also, being omniscience entails no knowledge that is not true and isn't represented in His reality by the truth. Lies and "false beliefs" of unbelievers are not knowable to God, because God only knows what is true in reality and this excludes all falsities and "false belief". Falsities and "false belief" only reside in the minds of the terminally ignorant who call themselves unbelievers, they openly reject God's truth and reality, destining themselves to wallow for eternity in the abyss.
These people are easily identifiable, they disbelieve that belief is capable of making the truth and reality known to them and have passed judgment on themselves, by rejecting the very means by which God has ordain to make His truth and reality known.
But believers believe that belief is capable of making His truth and reality known to them.
God is a Believing Mind that creates other believing minds in order to know and share His truth and reality and His Kingdom with. And that is why He refers to believers as His children; they share His truth and reality with Him by believing as He believes and His Holy Spirit makes this occur by literally believing in the believer through His indwelling of His Spirit of truth and reality.