Why do I doubt my salvation?
When someone begins to doubt his salvation, one of the first things he will want to know is, "Is this the Devil trying to make me doubt, or is this the Holy Spirit trying to show me that I am lost?" The pursuit of trying to answer this question, however, will often distract the person from the real question he needs to answer, which is not, "What is causing me to doubt?", but, "What will cause me to believe?" The Bible says in 1Co 3:11,
For other foundation can no man lay than that is laid, which is Jesus Christ.
So Jesus is the foundation of the believer's faith. Several years ago, there was a house I wanted to purchase out in the country. It was a nice home, but there were cracks in the bricks and the doors were uneven at their frames. Clearly the house was not settled properly. What did we have to do? We had to check the foundation. And, when we did, we found that it was in bad need of repair.
Our faith is very much like that house - it must have a good foundation to settle itself upon. And, if your faith is not settled, then you better check your foundation; because your trouble lies somewhere in your comprehension of the doctrine of Jesus Christ. Once the foundation is repaired, the faith will finally have a place to rest, and sing
"How firm a foundation, ye saints of the Lord, is laid for your faith in His excellent word!"