Absence of Prayer and Bible Reading
One of my old seminary professors wisely said that prayer is the pulse of the believer’s spiritual temperature.
If there’s a slowing or decreasing pulse in prayer, then there is spiritual decay, and the fellowship between them and God is affected.
Add to that a lack of regular Bible reading and you have a recipe for stunting your spiritual growth.
I have counseled so many people who are struggling with their faith. They begin to doubt their salvation, and then they stop reading the Bible altogether.
It is a self-replicating cycle. They pray less; they read less. The less they pray and read, the more they get into the habit of doing neither.
Reading the Bible will lessen your doubts. Not reading the Bible will increase your doubts. The exact same thing goes for prayer.