Another source of danger against which we should be constantly on guard is the reading of infidel authors. Such works are inspired by the enemy of truth, and no one can read them without imperiling the soul. It is true that some who are affected by them may finally recover; but all who tamper with their evil influence place themselves on Satan's ground, and he makes the most of his advantage. As they invite his temptations they have not wisdom to discern or strength to resist them. With a fascinating, bewitching power, unbelief and infidelity fasten themselves upon the mind. CT 135.3
We are constantly surrounded by unbelief. The very atmosphere seems charged with it. Only by constant effort can we resist its power. Those who value their salvation should shun infidel writings as they would shun the leprosy. CT 136.1