Here is how many Christians think of “getting saved:” You realize you’re a sinner and you need Jesus to save you. So you approach Him and ask. Of course He says, “Yes,” writes your name in the Lamb’s book of life, and gives you a “certificate” of salvation. If you begin to doubt whether or not you are really “saved,” you go back and replay the moment of your conversion.
Wrong image, I believe. Here’s the problem with it: What if you begin to ask, as I did, “Did I really feel sorry enough for my sin? Did my life change enough after I asked Him into my heart? Did I understand enough about Jesus, or my sin, or grace, when I prayed?” Uh-oh. Better ask again. Back you to go to Jesus, asking Him again to save you, and you feel better for a while. You can do this as much as you want until you meet Jesus in heaven, at which point you might finally be absolutely assured that you’re going to heaven.
That’s not how the Bible depicts salvation. Re-imagine the above example, but this time when you come to Jesus, instead of asking Him for a “certificate” of salvation, you tell Him that you believe what God’s Word says about His Lordship and His completed work at the cross. You then hop up into His arms, now depending on Him to carry you to heaven. You are leaning your weight on what He did, not on what you will do, to get you there.
If you begin to doubt whether or not you really belong to Jesus, what should you do? Do you go back in your mind to that moment when you first hopped up into His arms? You could. But perhaps it would be easier simply to think about where you are currently resting your weight. “Belief” is resting your weight on Christ’s finished work, and that is something you never stop doing. The way you know you are doing it now is not by remembering when you first started doing it, but by reflecting on the present posture of your heart. Your present posture is better proof than a past memory.