All that actually has to do with salvation knowledge is written many times in the New Testament. The knowledge of what causes sin, what sin is, and how God delivers men from sin is there.
Bible distribution ministries send millions of N.T Bibles into the world in most known languages. The gospel is what Jesus commended to preach, not Moses. Billions are reached only by the preaching of the gospel of Christ, as written in the N.T.
If a person can't recognize his sinful state from the N.T Bible, reading from the old will not help. In fact, that hinders with a large burden not meant for outside of Israel. The 10 Commandments are embedded twice (Exodus 20:2-17 and again Deu. 5:6-21) with a total of 613 laws, directly linking them to the whole of Moses' law, through the end of Deuteronomy. Saying the Decalogue is separate from the rest of the laws is error. Those laws were not given to the Gentiles, who if not converting to Judaism had to wait for the Messiah Jesus to come offering them the New Covenant.
Notice Jesus never went on record quoting more than 6 of the 10 together.
Mark 10:19-21 (KJV)
[SUP]19 [/SUP] Thou knowest the commandments, Do not commit adultery, Do not kill, Do not steal, Do not bear false witness, Defraud not, Honour thy father and mother.
[SUP]20 [/SUP] And he answered and said unto him, Master, all these have I observed from my youth.
[SUP]21 [/SUP] Then Jesus beholding him loved him, and said unto him, One thing thou lackest: go thy way, sell whatsoever thou hast, and give to the poor, and thou shalt have treasure in heaven: and come, take up the cross, and follow me.
In verse 21 Jesus focused on the gospel, not Moses, not the Decalogue.
The rich man still lacked according to Jesus.
Keeping the 10 "from my youth" was not enough.
Preaching the simple gospel of Christ is the word of God unto salvation for those who believe it, and act upon it. For the majority of people in the world, even if they only had access to an Old Testament few if any could detect signs of the salvation through the gospel of Christ in it, but would end up mired in the law of sin and death and perish in it like the Jews did. Even if they did all 613 laws it wouldn't be enough.
Some say Paul endorsed the law for all because he learned about sin from the law. Well, he was a Jew, not a Gentile, who was an expert at the law. That sin must only be exposed through the law is error. The epistles agree, knowledge of sin and the way of salvation is what the New Testament is about.
Romans 2:11-16 (KJV)
[SUP]11 [/SUP] For there is no respect of persons with God.
[SUP]12 [/SUP] For as many as have sinned without law shall also perish without law: and as many as have sinned in the law shall be judged by the law;
[SUP]13 [/SUP] (For not the hearers of the law are just before God, but the doers of the law shall be justified.
[SUP]14 [/SUP] For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves:
[SUP]15 [/SUP] Which shew the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the mean while accusing or else excusing one another
[SUP]16 [/SUP] In the day when God shall judge the secrets of men by Jesus Christ according to my gospel.
Moses will not be presiding at the Judgment. It will be Jesus, and the judgment will be according to the full gospel of the New Covenant.