Petto was an English Independent puritan minister who was ejected in 1662 at the Great Ejection. He then continued to preach in a barn for ten years. Petto was a correspondent of Increase Mather. His work below on Covenant Theology was originally recommended by John Owen, and later recommended in 1820 by Thomas McCrie the elder, and 29 other ministers.
The Great Mystery of the Covenant of Grace: or the Difference Between the Old and New Covenant Stated and Explained. As republished in 1820, Reprinted in 2007 by Tentmaker
God, dealing with men as reasonable creatures, that act out of judgment and their own choice, urges duty (as believing, repenting, etc.) by arguments from the advantage of coming up to it, All that believe shall be saved; and the danger of neglecting it, such shall be damned, as Mark 16:16; Rom. 10:9; Rev. 3:20. Such general propositions do not express the full tenor of the covenant, but only are means towards the execution of it; for, the invitations extend to all nations, Matt 28:19; Mark 16:15 (since the death of Christ, not before, Ps. 147:19,20); whereas the covenant is only with the Israel of God, Heb. 8:8.
Now faith gives no right [in a strict causal-meritorious sense], John 1:12, ‘To as many as received Him, gave He power to become the sons of God, even to them that believe on his name.’ Jesus Christ is offered in the free promise of the gospel; faith, that consents or receives Him, and a right and title in Him; to the blessings of the covenant, it does not give one.
The Father offers righteousness in a way of gift, Rom. 5:17. Faith accepts the offer, receives Jesus Christ for righteousness, and so conduces to justification, Rom. 4:3. Abraham believed God, and it was counted to him for righteousness, i.e. it was reckoned a means unto righteousness; so verse 5. Not that faith itself was reckoned the least of that righteousness whereby we are justified, but a means for the applying of Jesus Christ, who is our righteousness…The act of God in justifying is to be answered by the act of faith, consenting to the offer of the gospel…
There are various acts of faith, that, by the concurrence of the divine spirit may evidence interest in the covenant.
1. By faith in the free promise such glorious discoveries of the grace and love of God in Jesus Christ unto sinners are afforded, as their hearts consent to the offer thereof… the heart stood immediately before at an infinite distance from the Lord Jesus, and was full of opposition against Him; but when there is a work of faith upon it, then divine power is exerted by the word or promise of the gospel, for the drawing it [the heart] off from all other objects to pitch it upon Jesus Christ alone for salvation in a way of free grace: then it accepts the blessed offer, when all arguments in the world before would not prevail with it.
I think the worst of sinners (even insensible ones) are immediately under the invitations and calls of the gospel; for they may be condemned for unbelief, as standing out against them—Mark 16:15,16; Matt 22:3,4,9,10; Rev. 3:17,20.