Glorious quote from puritan John Owen, pay attention to the last sentence:
[God] requires nothing of us (which we had all the reason in the world to expect that he would) to make atonement or satisfaction for our sins, that might compensate the injuries we have done him by our apostasy and rebellion; for whereas we had multiplied sins against him, lived in an enmity and opposition to him, and had contracted insupportable and immeasurable debts upon our own souls, terms of peace being now proposed, who could think but that the first thing required of us would be, that we should make some kind of satisfaction to divine justice for all our enormous and heinous provocations? yea, who is there that indeed doth naturally think otherwise? But quite otherwise; in the gospel there is declared and tendered unto sinners an absolute free pardon of all their sins, without any satisfaction or compensation made or to be made on their part, that is, by themselves,—namely, on the account of the atonement made for them by Jesus Christ. And all attempts or endeavours after works or duties of obedience in any respect satisfactory to God for sin or meritorious of pardon do subvert and overthrow the whole gospel.
(The Works of John Owen, ed. William H. Goold, vol. 3: Pneumatologia: A Discourse Concerning the Holy Spirit (Edinburgh: T&T Clark, n.d.), 377-378.)
Our works to earn merit with God and therefore pardon for sin in His eyes overthrow the gospel. Why? Because Jesus’ work has already done it for us, how arrogant are we to think we can add to what He has already done?