Why should we believe in complete forgiveness if we cannot understand it?
Complete forgiveness should be believed because Scripture teaches it, not because human reason can fully grasp it. Christ's finished work paid for all trespasses—past, present, and future—so believers are forgiven entirely, not by their own deeds but by what Christ accomplished on their behalf, even though it remains beyond comprehension this side of glory.
Les teaches from Galatians 2:20 that when we come under forgiveness, we are forgiven everything—past, present, and future. He stresses that we will never come into God's presence with sin on our back, so to speak, because it has all been paid for. This, he says, is beyond human comprehension. He admits he cannot understand it, but he believes it because that is what the Book teaches: we have been forgiven all our trespasses, not because of anything we have done, but because of what Christ accomplished on our behalf. That is what makes the Gospel so simple and yet so complex, and it will never be fully understood this side of glory.