Assurance of Salvation

Faith is the assurance of things hoped for, the conviction of things not seen. [Hebrews 11:1]
Assurance is, simply, faith that God's love for you overcomes any obstacle: not that his love merely has the potential to do so, but that it actually does. Sometimes you're very conscious of the fact that you've put a lot of obstacles between yourself and God. You see your sin, and the guilt and shame can make it hard to believe that God's love could surmount even this. Again. "Maybe he forgives others who are better at this faith-and-repentance thing, but surely he doesn't forgive me." That's called doubt. The bad news is, doubt is more than just unhelpful when it comes to feeling good about your relationship with God. Doubt is actually insulting to God. Sure, doubt might be genuine, honest, authentic on your part. But your doubt reflects on him, says something about him. How long will you let your doubts declare that God is not trustworthy, not gracious to save you from all your sins?
Doubt, like any other sin, is just another obstacle for God's love to overcome. The good news is, when Jesus climbed up that hill with the timber on his back, and let himself be nailed up for a spectacle, the message was most clear. Jesus' own body was like a banner held high for all to see, for all to remember; "God loves you." The Eternal Father abandoned his Beloved Son to suffer and die so that you would never taste that abandonment, but rather feast forever at the rich banqueting table of his love. He has loved you, and nothing can improve upon it… or undo it. There is no obstacle between you and God's love—whether in heaven or on earth—that has not already fallen at the foot of the cross. Believe it.
Reformation Theology