Puritan Thomas Watson on abusing the mercy of God, from his Body of Divinity:
Take heed of abusing the mercy of God. Suck not poison out of the sweet flower of God’s mercy.
Think not that because God is merciful, you may go on in sin; this is to make mercy your enemy.
None might touch the ark but the priests, who by their office were more holy; so none may touch the ark of God’s mercy but such as are resolved to be holy.
To sin because mercy abounds is the devil’s logic. He that sins because of mercy is like one that wounds his head because he has a plaster.
He that sins because of God’s mercy, shall have judgment without mercy. Mercy abused turns to fury. ‘If he bless himself, saying, I shall have peace though I walk after the imagination of my heart, to add drunkenness to thirst, the Lord will not spare him, but the anger of the Lord, and his jealousy, shall smoke against that man.” Deut 24:19, 20.
Nothing is sweeter than mercy, when it is improved; nothing fiercer, when it is abused; as nothing is colder than lead when taken out of the mine, and nothing more scalding when it is heated. Nothing is blunter than iron, yet nothing is sharper when it is whetted.
‘The mercy of the Lord is upon them that fear him.’ Psa 103:17. Mercy is not for them that sin and fear not, but for them that fear and sin not. God’s mercy is a holy mercy; where it pardons it heals.
Truly may God through Jesus Christ have mercy on us who have many times shown our lack of faith in the unfettered mercy of God through Christ in using the promise of mercy to scorn and trample that very mercy promised.