In his Theodicy Leibnitz argues, like not a few predecessors, that this universe must be regarded as the best of all possible universes.
The former distinctly argues against the idea of a deterioration of man in the past.
The fourth argues for the orthodox belief of the two natures and one person of Christ.
Adam Ferguson (Institutes of Moral Philosophy, p. 119, new ed., 1800) argues that " the desire for immortality is an instinct, and can reasonably be regarded as an indication of that which the author of this desire wills to do."
He nowhere formally argues for the truth of theism.