To live with a sin conscience is always being aware of our sin and of those that are sinning around us. When our mind is consumed with a constant awareness of sin, it is difficult to accept and live in the freedom of God's grace.
God's plan wasn't for us to be ever conscience of our sins, but instead, to be set free from the bondage of sin. He desires for us to renew our mind and to be ever conscience of this gift of grace that covers all our sin.
Understanding this great exchange of our sin for this unlimited gift of grace, will create a deep appreciation and love for our Savior. We no longer are consumed by sin conscience, but now live in an awareness of this gift of AMAZING GRACE, and we now are consumed with the love of Christ. This truly is the "great exchange".