A classical theists attempts to “prove” God’s infinite perfection:

233. Thesis II. God is infinitely perfect.

Explanation. We mean by a perfection any real entity, anything which it is better to have than not to have. A being is infinitely perfect when it has all possible entity in the highest possible degree. It is clear at once that God, being the cause of the world, must have all the perfections that are actually in the world; for there can be no perfection in the effect which is not in the cause. But besides, He must have, we maintain, all perfections that are intrinsically possible, i.e., all that imply no contradiction. We must, however, distinguish between pure perfections — i.e., such as imply no imperfection, e.g., knowledge, goodness, justice, power, etc.; and mixed perfections — i.e., such as imply some imperfection, e.g., reasoning, which implies that some truth was first unknown. Now, we mean that God has all pure perfections formally or as such, and the mixed He possesses eminently, i.e., in a better way, without any imperfections.

Proof. Whatever the necessary Being is, it is that necessarily; but God is the necessary Being; therefore, whatever He is, He is that necessarily. Therefore, if there is any limit to His perfection, that limit is necessary; i.e., further perfection is excluded by the very nature of His physical essence; in other words, the entity or perfection of His being would exclude some further perfection. But no perfection excludes other perfection, or is incompatible with further perfection; there can be no contradiction between good and good, entity and entity, but only between good and not good, entity and non-entity, perfection and imperfection. Therefore no perfection can exclude any other perfection; hence no perfection is excluded either in kind or in degree; therefore God is infinitely perfect.