A brief word on general vs. special revelation.
The salvific element of God’s revelation is particular to his revelation in the Lord Jesus Christ.

A question with which a vast majority of Bible teachers and church leaders are likely familiar goes something like this: “What does God’s grace and justice look like for those living in the remotest corners of the world who have never heard about Jesus and the cross?” Inquiries such as this, and those similar to it, often function as honest inquests into the heart and mind of God himself. This is to say that such questions, whether the questioner is aware or not, are freighted with massive theological implications. The essence of such inquiries is a discussion comparing and contrasting general revelation and special revelation.
General revelation is regarded as God’s self-disclosure through the auspices of nature, history, and humanity. Special revelation, by contrast, is God’s self-disclosure through distinct messengers or messages to distinct peoples at distinct times. Millard J. Erickson distinguishes between the two like this: “General revelation is God’s communication of himself to all persons at all times and in all places. Special revelation involves God’s particular communications and manifestations of himself to particular persons at particular times, communications and manifestations that are available now only by consultation of certain sacred writings” (122). The reductionist version of the juxtaposition between these two modes of revelation could be understood as nature versus the Word.
In his letter to the Romans, the apostle Paul appears to affirm, at least in part, the merits of general revelation through natural theology when he states, “For what can be known about God is plain to them, because God has shown it to them. For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse” (Rom. 1:19–20). This testimony, coupled with the psalmist’s anthem in Psalm 19 that relishes in the brilliance and resonance of creation writ large, would appear to supply evidence that nature itself is self-evident to God’s existence. As true as that may be, the marrow of debate, however, arises when one postures that such revelation is sufficient for salvation, that is, for justifying faith. Erickson continues by noting that such is the endgame after which natural theology hastens:
Natural theology . . . maintains not only that there is a valid, objective revelation of God in such spheres as nature, history, and human personality, but that it is actually possible to gain some true knowledge of God from these spheres — in other words, to construct a theology apart from the Bible. (129)
Citing Paul’s letter to the Romans for such an argument is tenuous, at best, especially when the breadth of Pauline theology is considered as a whole. Chapters 2 and 3 of Romans, specifically, seem to have as their objective the dismantling of such redemptive hopes through general revelation alone. “None is righteous, no, not one,” Paul affirms, “no one understands; no one seeks for God” (Rom. 3:10–11). The prevalence and presence of sin have marred and blurred the witness of natural theology, thus endowing the believer’s and the church’s obligations with a multiplicity of urgency. As Paul concludes: “How then will they call on him in whom they have not believed? And how are they to believe in him of whom they have never heard? And how are they to hear without someone preaching? And how are they to preach unless they are sent?” (Rom. 10:14–15).
While the witness of Scripture avers that humanity can, and should, come to some conclusion in the realm of theism, this does not equate to what bare evangelicalism would contend is salvific. An assent to bare theism does not correspond to the saving faith as announced in the gospel. Such is what St. James would seem to suggest when he states that even the devil’s minions are capable of theistic affirmations (James 2:19). The indisputable revelation of nature certainly can direct one’s gaze to the “objective, valid, rational revelation” of God himself, as Erickson summarizes John Calvin’s position on the matter.
[John] Calvin’s position . . . is the view that God has given us an objective, valid, rational revelation of himself in nature, history, and human personality. Regardless of whether anyone actually observes it, understands it, and believes it, even though it may well have been disturbed by the fall, it is nonetheless present. (136)
But, even still, the salvific element of God’s revelation is particular to the revelation of himself in the Lord Jesus Christ.
The end of general revelation, then, it would seem, is to bring humanity to its knees — to the very end of itself — both with the panoplied brilliance of creation and the palpable sense that that creation is infected. It is thus that the culmination of general revelation is primed to make way for special revelation, the fullness of which is the Word made flesh. As Christ himself testifies, “I am the way, and the truth, and the life. No one comes to the Father except through me” (John 14:6). As he is the Yes and Amen “for all the promises of God” (2 Cor. 1:20), so, too, is he the Yes and Amen of the Godhead’s redemptive resolve.
Works cited:
Millard J. Erickson, Christian Theology, 3rd edition (Grand Rapids, MI: Baker, 2013).
I've been enjoying your blog since I found it, I wanted to say how much I appreciate what you write before I disagree with you. You said, ' As true as that may be, the marrow of debate, however, arises when one postures that such revelation is sufficient for salvation, that is, for justifying faith.' But what I read is not that faith saves or justifies. It is by Grace you have been saved, through faith, and that not your own.(Eph 2 obviously) So it is grace that is justifying with faith only being a vehicle by which sovereign, illimitable grace sometimes acts. The crucial point is that our hope is not in faith of whatever sort, it is in a God who justifies men who we think He will not save and honestly think He should not save. We cannot confine Him to any means of salvation. He acts through any means He chooses, through no means when He chooses, and in spite of all means when He chooses. While it would be wrong for me to teach that for example baptism is salvific, if the Lord chooses He could use baptism as a sole and effective means of salvation in a particular case, even a ridiculous missionary hurling water at an ignorant crowd of natives.(I choose a deliberately offensive example.) The crucial distinction of justification by grace through faith vs justification by faith(a perfect formulation when used as antithetical to works but not perfect in all instances), takes us from an uncertain confidence in our own faith, made into an effective cause of salvation,-making the faithful their own saviors, to a hope in a Christ who cannot be bought or controlled into justifying us but may be trusted to justify us with no reason at all outside His own goodness and love.