In his book, Stop Asking Jesus Into Your Heart, J.D. Greear writes,
The Enemy – one of whose names in Scripture is “the Deceiver” – loves to keep truly saved believers unsure of their salvation because he knows that if he does they’ll never experience the freedom, joy, and confidence that God wants them to have. But he also loves to keep those on their way to hell deluded into thinking they are on their way to heaven, their consciences immunized from Jesus’ pleas to repent. (p.6)
How ironic that so often it does seem to be the case that many sincere believers in Christ who have no biblically valid reason to doubt their salvation lack assurance, while others who actually have every reason to doubt the validity of their own profession of faith often continue on in a blissful state of ignorance & delusion about the true state of their souls.
For the former, it is a painfully discouraging situation; for the latter it is truly, sadly, and (if left unchanged) eternally disastrous.
What solution does Greear suggest? That we stop asking Jesus into our hearts over and over again (which is something far too many a modern evangelical can identify with) and “start resting in the finished work of Christ” (p.11).
In other words, remind yourself often, not of some past (and sometimes often-repeated!) experience or decision (i.e. walking an aisle, praying the sinner’s prayer, etc.), but of the gospel itself – the finished work of the Lord Jesus Christ on your behalf! At the end of the day, the way to assurance is not so much to look within (essentially to look to yourself!), but rather to look to Jesus Christ and His perfect righteousness and death on the Cross for sinners.