He follows after sanctification, because he has received justification. He obeys the law, not in order to be forgiven, but because he has been forgiven. And the love meant, is Christ's redeeming love. Because God has blotted out all his past sin, the believer has the most encouraging of all motives to resist all future sin. Had God not pardoned the past, it would be futile to struggle in the future.
Justification also frees the soul for true Christian service.
The soul released from anxiety about itself, is free to exercise concern about others. The heart is at leisure from itself to set forward the salvation of those around. An Introduction to the Thirty-nine Articles, p. 194.