God's forgiveness - a strength against sin by Horatius Bonar

"Under law and its curse, a man works for self and Satan; under grace he works for God. It is forgiveness that sets a man working for God. He does not work in order to be forgiven, but because he has been forgiven, and the consciousness of his sin being pardoned makes him long more for its entire removal than ever he did before.
An unforgiven man cannot work. He has not the will, nor the power, nor the liberty. He is in chains. Israel in Egypt could not serve Jehovah. "Let My people go, that they may serve Me," was God's message to Pharaoh (Exodus 8:1): first liberty, then service. A forgiven man is the true worker, the true lawkeeper. He can, he will, he must work for God. He has come into contact with that part of God's character which warms his cold heart. Forgiving love constrains him. He cannot but work for Him who has removed his sins from him as far as the east is from the west. Forgiveness has made him a free man, and given him a new and most loving Master. Forgiveness, received freely from the God and Father of our Lord Jesus Christ, acts as a spring, an impulse, a stimulus of divine potency."

~ Horatius Bonar, God's Way of Holiness

http://www.dustandashes.com/230.htm

Horatius Bonar about John Bunyan’s Calvinism

"Pliable: The hearing of this is enough to ravish one's heart. But are these things to be enjoyed? How shall we get to be sharers thereof?
"Christian: "The Lord, the Governor of the country, hath recorded that in this book; the substance of which is, If we be truly willing to have it, He will bestow it upon us freely.”
~ John Bunyan, Pilgrim's Progress

Thus very simply and beautifully does Bunyan put the manner of our obtaining the glory. Some would call this too free. Some would say, Here is the way made far too easy, without any preparatory alarms and repentance. But there stands John Bunyan's idea of the way of a sinner's entrance into the kingdom; and let him who can improve or correct it do so. "The Lord, the Governor of the country, hath recorded that in this book; the substance of which is, If we be truly willing to have it, He will bestow it upon us freely."
John Bunyan's soundness of doctrine is well known. His Calvinism was of a very decided kind. His views of Christ's redemption-work were very precise. His belief as to the necessity of the Holy Spirit's work was undoubted; yet he delighted to set forth the gospel in all its scriptural simplicity, unencumbered with preparatory exercises and processes intended to make the sinner "fit for receiving Christ," and fit for having the peace of the gospel dispensed to him; and never did he state that free gospel more freely, that simple gospel more simply, than when, in the manifest fulness of his heart, he wrote the above sentence, and put it into the lips of his pilgrim:-- "IF WE BE TRULY WILLING TO HAVE IT. HE WILL BESTOW IT UPON US FREELY."

Such a sentence shines like a star; yes, like a star to a tempest-tossed sinner in his night of darkness. He asks, How may I be saved? how may I be made a worshipper? how may I become a temple? how may I be taken into the royal priesthood? God's answer is not, works, and pray, and wait, and get convictions, and bring yourself under the stroke of the law; but believe and live; believe in the Lord Jesus Christ, and thou shalt be saved. Likest in its naked simplicity to these divine utterances is that star- like sentence of the Puritan dreamer. It is but another form, in language all his own, of the concluding message of gladness dropped from heaven, as the great book of truth was about to be closed and sealed:-- "WHOSOEVER WILL, LET HIM TAKE THE WATER OF LIFE FREELY."

Too free! Too easy! Too simple! It will only make skin-deep professors! Another gospel! So say some whose idea of the gospel seems to be that of a work to be done by the sinner, not of a work which Christ has already done; whose exhortations to the inquirer are, Wait, pray, seek, wrestle, labour on, and possibly God may drop salvation into our lap; whose theory of a sinner's approach to a Saviour turns all upon the necessity of some long, laborious preliminary seekings, repentances, convictions, terrors, by which he is so humbled and broken, as to be at length in a right frame for Christ to bless him, in a right condition to be trusted with rest of soul;--whose largest grasp of the glorious gospel extends only to this, that it is good news for the qualified, for those who have been ploughed deep enough and long enough by the law.
Well: go to; go to, we say to such. Away and dispute the matter not with us, but with the Master. Ask Him why He "received sinners" at once, without preliminary work, or qualification, or preparation, or delay; why He said to the hardened profligate of Sychar, "Thou wouldst have asked, and He would have given"; to Zaccheus, "Make haste and come down, for today I must abide at thy house"; to the adulteress, "Neither do I condemn thee"; to the thief upon the cross, "Today shalt thou be with me in paradise." Upbraid Him with allowing three thousand of Jerusalem sinners, at one bound, and under one single message, to pass into the kingdom, instead of keeping them "waiting at the pool," or tortured by the law into gloomy fitness for the glad tidings: express your astonishment that He should have set such an example of rearing churches out of heathen idolaters in a single day,--Corinth, Ephesus, Colosse, Thessalonica, Philippi, without waiting for years before calling their members "saints," or permitting them to sit down at the table of the Lord; set up your foolishness against His wisdom, your presumption against His lowliness, your traditions against His commandments, your love of darkness against His joy in light; proclaim your amended gospel, the gospel of Galatia, "Except ye be circumcised, Christ shall profit you nothing"; but what will be the result of those amendments and restrictions on Christ's free gospel?”

- Horatius Bonar, The Rent Veil
http://www.ccel.org/ccel/bonar/rentveil.xiv.html