Actually, this doesn't follow either since all men understand there is a God innately "because that which is known about God is evident within them; for God made it evident to them" (See Roman 1). Yet, men suppress these truths, these innate ideas, in unrighteousness. By suppressing the truth, they can't be said to also believe these innate truths which God has revealed "within them," since belief is an assent to understood propositions. Therefore, the sin of unbelief extends to all those who suppress the truth in unrighteousness and not just those who disbelieve the gospel when they hear it. QED.
Where is Christ revealed in nature? Note I am not talking about God as general but specifically rejecting Christ as a Saviour. As Paul states:
Rom 10:13, 14 "For whosoever shall call upon the name of the Lord shall be saved. How then shall they call on him in whom they have not believed? and how shall they believe in him of whom they have not heard? and how shall they hear without a preacher?"
This clearly teaches that unless Christ is declared to them in the gospel then they are unable to be saved, i.e. Christ as saviour is not declared through the light of nature. As the
Canons of Dordt teach
"To be sure, there is left in man after the fall, some light of nature, whereby he retains some notions about God, about natural things, and about the difference between what is honourable and shameful, and shows some regard for virtue and outward order. But he is so far from arriving at the saving knowledge of God and true conversion through this light of nature" and goes on to teach;
"What, therefore, neither the light of nature nor the law can do, God performs by the power of the Holy Spirit through the word or ministry of reconciliation, which is the gospel of the Messiah, by which it has pleased God to save men who believe, both under the old and new dispensation...Under the old dispensation God revealed this mystery of His will to few. Under the new dispensation, however, He took the distinction between the peoples away and revealed it to more. The cause of this very distribution of the gospel is not to be ascribed to the worthiness of one people above another, nor to the better use of the light of nature, but to the sovereign good pleasure and undeserved love of God. Therefore we to whom so great a grace is granted, beyond and contrary to all we deserve, ought to acknowledge it with a humble and grateful heart. But as regards others to whom this grace is not given, we ought with the apostle to adore the severity and righteousness of the judgments of God..."
Now whilst all men are duty bound to love God and to worship him and serve him, this does not include having saving faith in Christ or even believing in him.
The heathen in deepest darkest Amazonia know there is a god by the light of nature but they do not know of Christ unless a preacher preaches Christ to them.
Therefore how is God able to justly condemn the heathen who have never heard of Christ for their not believing in him?
As Gill notes:
It is urged, that "it cannot be consistent with divine equity and goodness, to make that a condition of any man’s happiness, which he cannot know to be his duty, or knowing, cannot do. Hence it is evident, that the knowledge of any revelation made to Jew or Christian, cannot be necessary to the happiness of heathens in general, much less the practice of any purely Christian duty; and therefore faith in Jesus Christ cannot be necessary to the salvation of as many of them as have never heard of him." I answer; that the heathens will not be condemned and punished for their ignorance of that revelation which was never vouchsafed to them, nor for the non-performance of and purely Christian duty, such as baptism and the Lord’s supper; nor for not believing in Christ, of whom they have never heard, only for those sins which they have committed against the law and light of nature; but inasmuch as they are without any true knowledge of the way of atonement for sin, and without any revelation from God of the method of salvation from it, they must be considered as destitute of the means of grace, and as far from true happiness and felicity." (The Cause of God and Truth, Part 3, Chapter 8, pp 217)
Question: Is Christ revealled in nature or by the light of nature? If not then your point above does not apply...i.e. yes all are duty bound to believe in God but that is not the issue...the issue is wether they are duty bound to believe in Christ.
Those who are duty bound to believe the gospel are those who actually hear it. Jew and Greek are indiscriminately commanded to repent (change their minds) and believe (assent to the truth).
Repentance: All have broken the law and so all are duty bound to repent.
Faith: I affirm with Gill that "As for those texts of Scripture, I know of none, that exhort and command all men, all the individuals of human nature, to repent, and believe in Christ for salvation; they can only, at most, concern such persons who are under the gospel dispensation; and, in general, only regard an external repentance and reformation, and an historical faith in, or assent to, Jesus as the Messiah." (Gill)
Concerning Acts 17:
but now commandeth all men everywhere to repent; that is, he hath given orders, that the doctrine of repentance, as well as remission of sins, should be preached to all nations, to Gentiles as well as Jews; and that it becomes them to repent of their idolatries, and turn from their idols, and worship the one, only, living and true God: and though for many hundreds of years God had neglected them, and sent no messengers, nor messages to them, to acquaint them with his will, and to show them their follies and mistakes; yet now he had sent his apostles unto them, to lay before them their sins, and call them to repentance; and to stir them up to this, the apostle informs them of the future judgment in the following verse. Repentance being represented as a command, does not suppose it to be in the power of men, or contradict evangelical repentance, being the free grace gift of God, but only shows the need men stand in of it, and how necessary and requisite it is; and when it is said to be a command to all, this does not destroy its being a special blessing of the covenant of grace to some; but points out the sad condition that all men are in as sinners, and that without repentance they must perish: and indeed, all men are obliged to natural repentance for sin, though to all men the grace of evangelical repentance is not given: the Jews call repentance מצות התשובה, "the command of repentance", though they do not think it obligatory on men, as the other commands of the law. The law gives no encouragement to repentance, and shows no mercy on account of it; it is a branch of the Gospel ministry, and goes along with the doctrine of the remission of sins; and though in the Gospel, strictly taken, there is no command, yet being largely taken for the whole ministry of the word, it includes this, and everything else which Christ has commanded, and was taught by him and his apostles; Mat 28:20.
But no where is faith made a duty upon all men!
Saving faith is an assent to the propositions of Scripture, specifically the gospel.
The object of saving faith are are not bare axioms or propositions as Gill correctly teaches:
"An assent unto Christ as a Saviour, enters into the true nature of faith; not a bare naked assent of the mind to the truth of the person and offices of Christ; that he is the Son of God, the Messiah, Prophet, Priest, and King, such as has been yielded to him by men destitute of true faith in him, as by Simon Magus and others, yea, by the devils themselves (Luke 4:34,41). "Of all the poison, says Dr. Owen, which at this day is diffused in the minds of men, corrupting them from the mystery of the gospel, there is no part that is more pernicious than this one perverse imagination, that to "believe in Christ" is nothing at all but to "believe the doctrine of the gospel!" which yet we grant is included therein.’’
Such a proposition, that Christ is the Saviour of the chief of sinners, or that salvation is alone by him, is not presented merely under the notion of its being "true", and assented to as such, but under the notion of its being "good", a suitable, acceptable, and preferable good, and to be chosen as the good part was by Mary; as being both a "faithful saying" to be believed as true, and as "worthy of all acceptation", to be received and embraced as the chiefest good. Faith is an assent to Christ as a Saviour, not upon an human, but a divine testimony, upon the record which God has given of his Son, and of eternal life in him. Some of the Samaritans believed on Christ because of the saying of the woman; but others because of his own word, having heard him themselves, and knew that he was indeed the Christ, the Saviour of the world: true faith, in sensible sinners, assents to Christ, and embraces him not merely as a Saviour of men in general; but as a special, suitable Saviour for them in particular: it proceeds upon Christ’s being revealed "in" them, as well as "to" them, by the Spirit of wisdom and revelation, in the knowledge of him as a Saviour that becomes them; it comes not merely through external teachings, by the hearing of the word from men; but having "heard and learned of the Father", such souls come to Christ, that is, believe in him (John 6:45), not the doctrine of him only, but in him himself."
What worries me is that you turn faith into a mere intellectual assent to axioms.
You so deny a sinner can say with Paul:
1Ti 1:15 This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners;
of whom I am chief.
Gal 2:20 I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of
the Son of God, who loved me, and gave himself for me.
Once you remove that subjective element from saving faith you destroy it.
"That faith by which a man is said to he justified, is not a mere assurance of the object, or a bare persuasion that there is a justifying righteousness in Christ; but that there is a justifying righteousness in Christ for him; and therefore he looks unto, leans, relies, and depends on, and pleads this righteousness for his justification: ... And what is short of this I cannot apprehend to be true faith in Christ, as the Lord our righteousness."
Part of saving faith is saying Christ "gave himself for me". Now because faith contains this it cannot be a duty for how can the reprobate, those for whom Christ died not shed his blood be duty bound to believe that he did! So if you are correct and faith is a duty you have said that God has placed all men under the duty to believe a lie and then punishes them for not believing this lie!
http://www.pbministries.org/books/gill/Practical_Divinity/Book_1/book1_06.htm
http://www.pbministries.org/books/gill/Practical_Divinity/Book_1/book1_04.htm