Basically my main concern is "can God impute Christ's righteousness to people who have never heard of Jesus Christ or the gospel?
Does the Bible teach us that it is absolutely necessary for the gospel to be heard or read or understood to bring about conviction and repentance? Or can people follow their conscience and have the Holy Spirit renew them without the use of the gospel?
The Holy Spirit came to give witness to Christ. He will not nor cannot renew one, and leave that person worshipping a pole for the rest of his life.
AS far as reading or hearing or understanding, I reserve commenting on these subjective thoughts. How much reading, how much hearing? And what words exactly? How much understanding? Scripture presents God who came in the flesh, to save His people from their sins.
Now there was a man in Jerusalem, whose name was Simeon, and this man was righteous and devout, looking for the consolation of Israel, and the Holy Spirit was upon him. And it had been revealed to him by the Holy Spirit that he should not see death before he had seen the Lord's Christ. And inspired by the Spirit he came into the temple; and when the parents brought in the child Jesus, to do for him according to the custom of the law, he took him up in his arms and blessed God and said,
Lord, now lettest thou thy servant depart in peace, according to thy word; for mine eyes have seen thy salvation which thou hast prepared in the presence of all peoples, a light for revelation to the Gentiles, and for glory to thy people Israel.
Every Elect will confess Jesus is the consolation of Israel, the Christ, the Messias. How they express it, or how they repent, or how they understand it is moot. But hey will know "I was blind and Now I see..."
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 Lordís 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)
The Indians who have never heard of Christ, are not bound to believe in him; nor will they be condemned for their unbelief; but for their sins against the light of nature, they have been guilty of; (see Rom. 10:14; 2:12). Where a revelation is made, and that is only external, and lies in the outward ministry of the word, declaring in general such and such things, concerning the person and office of Christ, men are obliged to give credit to them, upon the evidence they bring with them, and for their unbelief will be condemned; not because they did not believe that Christ died for them, to which they were not obliged; but because they did not believe him to be God, the Son of God, the Messiah, and the Saviour of men. Where the revelation is internal, "By the Spirit of wisdom, and revelation in the knowledge of Christ"; showing to men their lost estate, and need of a Saviour; acquainting them with Christ, as an able and willing Saviour; setting before them the fulness and suitableness of his salvation; such are, by the Spirit and grace of God, influenced and engaged to venture their souls on Christ, and to believe in him, to the saving of them; but then the first act of faith, even in such, is not to believe that Christ died for them; for it is the plerophory, the full assurance of faith to say, "He hath loved me, and given himself for me!" (Gal. 2:20).