We believe that "all Scripture" contains inspired, divine teaching (2nd Timothy 3:16-17). When Paul wrote down these words, he must have thought primarily about the first part of our Bible, because the writings of the New Testament were not yet complete. We agree with him. It is the same God who faithfully accompanied humankind from creation until today. In one of his speeches, Paul defended his faith with these words:
"But this I confess unto you, that after the Way which they call a sect, so serve I the God of our fathers, believing all things which are according to the law, and which are written in the prophets." (Acts 24:14, ASV)
Paul had to clear up certain misunderstandings in his day and even today there is still some confusion about New Testament Christianity. At the same time, most Bible believing people will agree that we don't have to follow all of those things written in the first part of the Scriptures. No one believes for example that God still requires animal sacrifices or wants us to build a large ship. Each of these commands are God's word, yet not each Word of God is His direct will for us today.
But of course we all truly believe in the words of the Law of Moses and the Prophets. If we do so we find that these words lead us further than just toward the end of their respective time. God once told Moses:
"I will give them a prophet from among themselves, like you, and I will put my words in his mouth, and he will say to them whatever I give him orders to say. And whoever does not give ear to my words which he will say in my name, will be responsible to me." (Deuteronomy 18:18-19)
The second part of the Bible picks up on texts such as this (see Acts 3:19-26). Several hundreds of Old Testament promises find their fulfillment in Jesus. When we read in the first part of the Bible, we see how the coming of God's son was foreshadowed (Hebrews 10:1). Isn't it just logical if we listen to the words of Jesus as God's final word for us today?
"In times past the word of God came to our fathers through the prophets, in different parts and in different ways;
But now, at the end of these days, it has come to us through his Son ..." (Hebrews 1:1-2)
What He began with Noah, Abraham and David, God continued with Jesus. However the covenant made through Moses was broken many times. For that reason a new covenant was announced by Jeremiah the prophet (see Jeremiah 31:31-34). People who belong to this new covenant have the word of God already written on their hearts. No one is born as a Christian, but "Everyone whose ears have been open to the teaching of the Father comes to me." (John 6:45)
Under the new covenant, all disciples of Jesus together help build a spiritual temple (1st Peter 2:4-5). Here, the priesthood of all believers is a reality (1st Peter 2:9). We are no longer under the command to give the tenth part of our income. Everyone may give according to his heart (2nd Corinthians 9:7). While there was a division between Jews and other peoples in earlier times, God now wants to unify all people in his son (Ephesians 2:13-22).
In short: Jesus has inaugurated a new era through His death on the cross and His victorious resurrection. We confess Him as our King who sits at the right hand of God and will reign until all evil is overcome (Psalm 110; 1st Corinthians 15:25-26). This teaching is confirmed in all of Scripture and handed down to us especially in the New Testament. That's what we believe.