I've had periods of my life when I've doubted and I imagine you have as well. Like the father of Mark 9:24 I've cried out, "I do believe; help my unbelief!" Wilson exhorts me and you to battle our unbelief in the following ways...
Concentrate on the historical fact of the cross. Read the gospels and read books about the cross and reflect on why Jesus died.
Do not seek refuge or advice with those who would shame you for doubting. In my doubts I need the gospel and I need the kind of community that neither shames nor coddles.
Pray. Ask the Lord to increase your faith. Pray as if you do believe. Cry out to Him in boldness and in honesty.
Refocus your doubts toward your own failings and inability. Wilson writes that we should doubt ourselves, doubt our doubts. In other words, despair of yourself! When you realize your utter insufficiency you are better able to trust the Lord's sufficiency and grace.
Finally, read your Bible. Meditate on the promises of God. Christ's righteousness covers your doubt! Wrestling with unbelief is actually an indication of belief.
As I've written before, we all go through stages of our journey when the Lord seems distant and we are forced to wrestle with the reality of our faith. May we turn to Him in the smallness of our mustard seed sized faith and cry out for help. The Lord is faithful and we can trust Him to remove all doubt as He brings to completion His good work in us! Yes and amen!