I can't speak for all Christians, but there were times I knew that I knew that I knew. It was those moments which left an abiding faith that God is more real the material world. So in the same way unbelievers can't get rid of doubts altogether, I can't get rid of my faith.
The other way of knowing IMO is that certain scriptures suddenly have new, applicable meaning you were too dumb to appreciate before.
The other way of knowing IMO is that certain scriptures suddenly have new, applicable meaning you were too dumb to appreciate before.