Thomas Watson's Final Rule For the Right Understanding of the Ten Commandments
Dr. Watson in his final rule looks at our inability to obey the law of God, and the grace of God to us in this respect.
Rule 8. Although we cannot, by our own strength, fulfil all these commandments, yet doing quoad posse (what we are able), the Lord has provided encouragement for us. There is a threefold encouragement.
(a) That though we have not ability to obey any one command, yet God has in the new covenant, promised to work that in us which he requires. 'I will cause you to walk in my statutes.' Ezek 36:27.
God commands us to love him, but how weak is our love! But God has promised to circumcise our hearts, that we may love him: 'And the Lord thy God will circumcise thine heart, and the heart of thy seed, to love the Lord thy God with all thine heart, and with all thy soul, that thou mayest live.' Deut 30:6
He that commands us, will enable us.
God command us to turn from sin, but alas we have no power to turn; therefore he has promised to turn us, to put his Spirit within us, and to turn the heart of stone into flesh: ' A new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh.' Ezek 36:26.
There is nothing in the command, but the same is in the promise.
Therefore, Christian, be not discouraged, though you have no strength of your own, God will give you strength. 'Thou hast wrought all our works in us' Isa 26:12.
(b) Though we cannot exactly fulfil the moral law, yet God for Christ's sake will mitigate the rigour of the law, and accept of something less than he requires. God in the law requires exact obedience, yet will accept of sincere obedience; he will abate something of the degree, if there be truth in the inward parts. He will see the faith, and pass by the failing. The gospel remits the severity of the moral law.
(c) Wherein our personal obedience comes shortly, God will be pleased to except us in our Surety. 'He hath made us accepted in the Beloved.' Eph 1:6 Thou our obedience be imperfect, yet, through Christ our Surety, God looks upon it as perfect. The very service which God's law might condemn, his mercy is pleased to crown, by virtue of the blood of our Mediator.