John Flavel (The Method of Grace, p. 154):
Let all that are under inward troubles for sin, take heed of drawing desperate conclusions against themselves, and the final state of their own souls. Though your case be sad, it is not desperate; though the night be troublesome and tedious, keep on in the way to Christ, and light will spring up. To mourn for sin is your duty; to conclude there is no hope for you in Christ, is your sin. You have wronged God enough already, do not add a further and greater abuse to all the rest, by an absolute despair of mercy. It was sin formerly to presume beyond any promise, it is your sin now to despair against many commands. I would say as the apostle in another case, I would not have you mourn as men that have no hope: your condition is sad as it is, but yet it is much better than once it was. You were once fully of sin and void of sense, now you have the sense of sin, which is no small mercy. You were once quite out of the way and method of mercy, now you are in that very path wherein mercy meets the elect of God. Keep hope, therefore, at the bottom of all your troubles.