Is it a sin to have intrusive thoughts?

from the old testament

• God knows that Christians can have intrusive thoughts. He looks deeper than the fleeting image, "…for the LORD searches all hearts and understands every plan and thought," (1 Chronicles 28:9).
• Sometimes we can forget that God knows the intent behind our thoughts. He knows the wicked will blaspheme His name: "In the pride of his face the wicked does not seek him; all his thoughts are, 'There is no God'" (Psalm 10:4),
• God knows how fragile our thoughts are (Psalm 94:11).
• Even if our actions lead to an intrusive thought, God will be our consolation (Psalm 94:19).
• Psalm 139:2 says, "You know when I sit down and when I rise up; you discern my thoughts from afar." God is aware of our thoughts, but He is also discerning.
• If we are feeling overwhelmed by intrusive thoughts, we should ask God to search us. We can pray David's prayer from Psalm 139:23-24: "Search me, O God, and know my heart! Try me and know my thoughts! And see if there be any grievous way in me, and lead me in the way everlasting!"

from the new testament

• Second Corinthians 10:3-5 details how to take control of intrusive thoughts. First, we should relax and realize that intrusive thoughts cannot be completely conquered by earthly methods. Spontaneous blasphemy and harmful inclinations are aspects of spiritual warfare. Next, we should take the thought captive—capture it, break it down, determine if there is any truth in it, and vanquish the lies. We can study and memorize Scripture so that we are ready with the truth the next time the thought pops up.
• If we fill our minds with ungodly things, blasphemous and harmful thoughts will be more likely to come up. Philippians 4:8 tells us, "Finally, brothers, whatever is true, whatever is honorable, whatever is just, whatever is pure, whatever is lovely, whatever is commendable, if there is any excellence, if there is anything worthy of praise, think about these things."
• God is easily able to judge between a thought, a belief, and an intent (Hebrews 4:12).

implications for today

An intrusive thought is an involuntary, unwanted image, phrase, or impulse. They are very common; nearly everyone has them from time to time. Sometimes they are of a violent nature, other times they are sexual. Often, they are blasphemous or induce great fear of having done a ritual incorrectly. They can be quite disconcerting, especially when they are completely contrary to what a person actually believes.

To help with our intrusive thoughts, we should be aware of God’s character and test every intrusive thought against God’s Holy Word. We must also be very careful about what we are putting into our minds. We should guard our eyes, since they are the “lamp to the body” (Matthew 6:22) as well as put in our minds godly things as highlighted in Philippians 4:8.

Sometimes repeatedly capturing the thought and refuting it with God's Word doesn't make the thought stop because intrusive thoughts can be overwhelming and impossible to control. This is one of the primary symptoms of obsessive compulsive disorder and a lesser symptom of many other disorders. [like what? Either name a couple or eliminate the phrase “and a lesser symptom…”.] If the intrusive thoughts are particularly debilitating, we should see a medical doctor or a qualified counselor. God has provided us with physicians who can care for the body as well as those who care for the soul, and we should take advantage of their expertise.

No matter how much turmoil we feel over our intrusive thoughts, God understands us (Psalm 139:2) loves us very much (1 John 4:16) and is the Giver of incredible peace (John 14:27).