When studying the Bible, one must realize that there are two sections: the Old Testament is an account of God’s dealings with the Jews and the law that Moses brought to them from Mt. Sinai (Nehemiah 9:13). This part of the Bible is history, and we should read it to be informed about things of that time (Romans 15:4; 1 Corinthians 10:11).
The New Testament is to be our authority in all things pertaining to salvation, the church, worship, etc. For example, if one is going to prove that instrumental music is not to be used in the worship service, that person would have to prove such by the New Testament.
If one were going to prove that Sunday, not Saturday, is the day of worship, he should do so by the authority of the New Testament. The reason for such is because the Old Testament has been taken away by Christ’s death, for his blood brought about the new covenant (Mark 14:23-24). The author of the book of Hebrews said that a covenant cannot be in force as long as one who made it is alive, but it takes effect after the creator dies (Hebrews 9:11-28).
The Old testament is history, and the New Testament is for us to pattern our lives.