In his commentary on Chapter 4 of the Gospel According to Saint John, St. Thomas has an interesting argument about knowledge of God:
It should be pointed out that, as the Philosopher says, knowledge of complex things is different than knowledge of simple things. For something can be known about complex things in such a way that something else about them remains unknown; thus there can be false knowledge about them. For example, if someone has true knowledge of an animal as to its substance, he might be in error touching the knowledge of one of its accidents, such as whether it is black or white; or of a difference, such as whether it has wings or is four-footed.
But there cannot be false knowledge of simple things: because they are either perfectly known inasmuch as their quiddity is known; or they are not known at all, if one cannot attain to a knowledge of them.
Therefore, since God is absolutely simple, there cannot be false knowledge of Him in the sense that something might be known about Him and something remain unknown, but only in the sense that knowledge of Him is not attained.
Accordingly, anyone who believes that God is something that He is not, for example, a body, or something like that, does not adore God but something else, because he does not know Him, but something else.
You either have true knowledge of God, according to St. Thomas, or you have no knowledge of Him at all.
And since to adore something requires knowledge of that something, you either have true knowledge of God, or what you adore is not God.