If you trust Jesus, justification gives hope to any and every bad day you might have. Whether it really is a Monday or just feels like one because of a fresh sense of your own sinfulness, the once-for-all events of Good Friday and Easter Sunday grant grace to “a case of the Monday’s.”
God’s work of justification is the one act of God that blots out the sum total of your sin because of the saving work of Jesus.
Justification blesses your worst days because it imputes to you the perfect righteousness of Christ and his eternal and unbroken best days. Theologian William G.T. Shedd explains this hope-giving truth:
The justification of a sinner is an all-comprehending act of God. All the sins of a believer, past, present, and future, are pardoned when he is justified. The sum-total of his sin, all of which is before the Divine eye at the instant when God pronounces him a justified person, is blotted out or covered over by one act of God. Consequently, there is no repetition in the Divine mind of the act of justification; as there is no repetition of the atoning dath of Christ, upon which it rests. [Quoted by Anthony Hoekema, Saved By Grace, 180]
God’s work of justification is the one act of God that blots out the sum total of your sin because of the saving work of Jesus. God has good news for every single one of your worst days.