The more analytical philosophers of religion would hone in on the first criteria of religious truth that the Enlightenment thinkers held to, I find the second criteria more interesting and more disturbing. Thus, for now I will bypass the first criteria and focus on the second.
The British thinker Matthew Tindal held that Reason was not enough of a standard to hold Religion up to. A purely Reasonable Religion, for Tindal, was missing the point of religion. According to Tindal, "all beliefs and practices must be judged not only by natural reason but by their ability to promote human happiness." (Modern Christian Thought, Livingston, pg. 23) If we were to only judge things on their logical consistency, we would only be left with a mind full of prepositions and ideas, and our lives would not be better. Therefore, we have to not only test the reasonableness of religion, we need to test of how it effects our everyday life and mood.
Tindal's thought continues in this vein: "God's purpose in creation was not for His own glory or advantage, but the happiness of His creatures. God thus demands of us only what will contribute to our perfection and happiness." (pg. 23, italics added) We attain this happiness and perfection through discerning the universal, unchanging truth and putting it into action. Put another way, we become happy by reasoning out morality and putting it into action. "The end of religion, then, is morality, for true religion consists 'in a constant disposition of mind to do all the good we can, and thereby render ourselves acceptable to God in answering the of our creation.'" (pg. 24)
If God's purpose in creation was to make us happy, then our purpose in life is not to make God happy. Our purpose in life is then transformed into a mission to make ourselves happy through the practice of correct action. On top of this, the end of religion is not God, but ourselves. Religion exists solely for our sake. Our morality comes from God, but is not for God.
The French thinker Voltaire took this idea further. Voltaire held that religion should be the practice of morality. His ideal church service would consist of of "primarily...praise and adoration and lessons in morality." (pg. 28) This is what the Church should become according to Voltaire. It should become a place to gather and to be told how to act and behave according to a certain set of moral rules. In doing so, we strip the doctrines and creeds of content that do not hold up to our conception of morality. Tindal held that "Anything in religion that is not required of our moral life should be removed, for the more one 'is not of a moral nature, the less he will be able to attend those that are.'" (pg. 24) According to Livingston, Tindal went so far that he was "willing to call everything in religion superstitious and dangerous which is not directly conductive to morality." (pg. 24)
Not only is this what the Church should become according to Tindal and Voltaire, but it has become this. We, as a Church, have become ignorant of doctrines and their meaning. We have gotten rid of the sacraments and replaced them with moral lessons. When we hear a sermon, we do not want to hear about the divine homoousia and the internationality of the Trinity. We want to hear how to be better people and how to be happier. We get bored by theology and cling to morality. The religion of Christianity in parts has become a religion of morality. This leads to not only a prevalent anti-intellectualism but a perversion of the Gospel. We want God to be for us, but we do not want to be for God. We have reversed how the relationship between humanity and God operates.