Such is the proper knowledge of God that we have by demonstrations. But that is not sufficient for the final happiness of man. But happiness is the end and perfection of the human species, since all men naturally desire it. Happiness then is a common good, possible to accrue to all men, except in cases where an obstacle arises to deprive some of it. Such scientific knowledge then is not the essence of human happiness.
Happiness excludes all misery.
But deception and error is a great part of misery. Now in the knowledge of God by demonstration manifold error may be mingled, as is clear in the case of many who have found out some truths about God in that way, and further following their own ideas, in the failure of demonstration, have fallen into many sorts of error. Happiness consists in perfect activity.