If we take a careful look at the beginning of every book in the New Testament, we’ll see that it is always addressed to the saints. Every time the writer directs his words to a specific people: the saints in Christ Jesus who are in a specific place.
No one book in the Bible is addressed to the whole world or anyone who is not a believer. The addressee is always named very specifically. This is very important, because it helps us see that the Bible has been written for a specific people.
Even in the Old Testament we find that God’s Word was always delivered to a specific people: ancient Israel. They were chosen by God from among all the nations on Earth, to be holy and to know the true God and His Word. Still, they “were not all Israel, who were of Israel” (Romans 9:6-7)
Ancient Israel was always in trouble because of their unbelief. Even when God delivered them from the bondage of Egypt, with signs and wonders and with an outstreched arm, they were a stiff necked (very proud) people and rebellious. God promised that they were going to be judged and destroyed for their unbelief and that He was going to take His Word from them and give it to another people (the Gentiles) and they would obey Him.
Certainly, not all Gentiles will believe, but only those who He would call. God was going to choose out of all nations in the world, a people for Himself. That was the promise or the covenant God made with Abraham, the Father of many nations.
To say that the Bible is the Law for the whole world is a griveous mistake, because it was never God’s purpose to save the entire world. He chose His people from before the foundation of the world, and gave them His Word, the Bible, to make them know Him and to help them in their pilgrimage on this present evil world.
The children of God, holy and elect of God, look for the glorious appearing of their Savior and look forward to the promise of a new heaven and a new earth where righteousness will dwell. That event is still in the future, but we patiently wait for our Lord Jesus Christ’s return.