“The violent entry of these blasphemous temptations into the Christian's mind by a word, does it not seem strange that when the Christian was an enemy to God he dared not venture into this sin because of its monstrous nature, yet now that he begins to love God these blasphemies, which were too big and horrible before, would fill his mouth?
The violent entry of these blasphemous temptations into the Christian's mind betrays their breeding place-- Satan, not he person's own heart. They flash like lightning into the person's thoughts before he has time to decide what he is doing. Lust, which overflows from the heart is, on the other hand, ordinarily more gradual in its persuasion.
Not only their sudden violence, but their incoherence with the Christian's former thoughts, heightens the probability that these temptations are darts shot from the devil's bow. Peter was known to be a member of Christ's company by his voice: "But again he denied it falsely and disowned Him." Mark 14:70. He talked like them and was judged to be one of them. On the contrary, we may say of these blasphemous thoughts, "They are not the Christian's. Their language shows them to be the belching of a devil, not the voice of a saint. If they were woven by the soul, they would be something like the whole piece from which they were cut." There is ordinarily continuity in our thoughts, like a circle rising out of another circle in stirred water.
Sometimes as the Christian worships God, and intruding blasphemous thought barges in like a rude stranger. The tenant never ushers in a thief. If a holy thought surprises us when we are far from heavenly meditation, we may take it as a pure moving of Christ's Spirit. Who but He could appear so suddenly in the midst of the soul when the door is shut, even before the person can turn his thoughts to open it for Him? He betrays their breeding place--Satan, not the person's own heart.”
Quoted material from, ”The Christian in Complete Armour Daily Readings in Spiritual Warfare” by Gurnall and James S Bell. http://www.moodypublishers.com/pub_productDetail.aspx?id=41823&pid=53617