It is called the New Testament because it was written after the Old Testament and tells of the new "testament" which means covenant or agreement between God and man. The old testament or covenant with Moses was fulfilled in Christ and this is the story of the New testament.
The answer lies in the definition of Testament. Testament in this context means Covenant or Contract between God and man. The Old Testament was the old Covenant that was struck strictly between God and Abraham and Abraham's descendants (the Hebrews) which required religious acts of obedience from man to be good enough to enter heaven when a person failed to hold up their end of the contract it was called a sin if a person sinned then they could make up for it with a religious ceremony that required the blood of a perfect Lamb. The New Testament was prophesied about in the Old Testament. The New Testament is the New Covenant struck between God and all humans not just the Jews. What is different in this new contract is that Christ paid for all of sins with His life since it is impossible for us not to sin. Thus through Accepting Christ's gift of Sacrifice and Believing He has power over death as described in the Resurrection passage then we will be saved.
Additional Answer:
Just to add to the above answer so interesting points to consider.
If you had lived 2000 years ago and had asked the Apostle Peter, Paul or John about the 'Old Testament' or the 'New Testament,' they would have had no idea what you were talking about. These terms were coined by men long after the books of the Bible were written. The 1st use of the term 'New Testament' for the Greek Scriptures is not found until a century or more after the death of the Apostles.
Some people today assume that the Old Testament with a God of wrath, as old or obsolete needing to be replaced by the New Testament with a God of love. This is totally a wrong conclusion as Christ taught we are to live by every word of God and quoted many times from the OT Scriptures (only Scripture around at His time).
Some Bible translations do have a few places where they use the designations 'Old Testament and New Testament' However, the word translated testament is also the word for 'covenant' both Old and New and is a better translation.
Considering that the Bible has 773,000 words and nearly 80% of them are written in the Hebrew Scriptures, it would be illogical to disregard this history of God's revelation, His revealed way of life, future prophecy and the promises He made to all mankind.
Acts of the Apostles is called the history book of the New Testament because it is strongly believed to record the actual history of the early Church. In the words of Sir William Ramsay, "Luke is a historian of the first rank; not merely are his statements of fact trustworthy...this author should be placed along with the very greatest of historians." This is now strongly disputed.
Uta Ranke-Heinemann (Putting Away Childish Things) says that anyone familiar with recent scholarship would laugh at Ramsay's claim, and says that the whole book is a work of Propaganda aimed at Gentile Christians and Gentiles who have not yet become Christians. John Dominic Crossan (The Birth of Christianity) says that Acts of the Apostles, traditionally regarded as an important history of Christianity in Apostolic times, is theology rather than history. Hans Joachim Schoeps writes that Acts has been believed much too readily, saying that Acts is only a retrospective view of Christian origins written by one party - the winners. The book of Acts is not a history but is widely considered to be about history.
It is called the new Testament.
The Bible is called testaments because there is 2 different testaments the new testament and the old testament the new testament is after Jesus was born and the old testament was before Jesus was born.
In the new testament only a total of four books are called the goospel books. They are the gospel of Matthew, the gospel of Mark, the gospel Luke and the last gospel the gospel of John.
The first four books of the new testament are commonly called the gospels (Matthew, Mark, Luke, and John). The first four books of the Bible as a whole (beginning with the new testament, are actually part of five books called the Torah, or Law, or "The Books Of Moses", Genesis, Exodus, Leviticus, and Numbers.
No. The Book of Acts is in the New Testament.
It is called the new Testament.
Yes, there is a book in the New Testament called "Hebrews"
No. The Bible consists of the Old and New Testament.
The word "Testament" means - agreement, covenant. So the New Testament can also be called the New Covenant.
The Bible is called testaments because there is 2 different testaments the new testament and the old testament the new testament is after Jesus was born and the old testament was before Jesus was born.
Christian Greek Scriptures known as the New Testament
Jesus is Called the Son of Man 88 Times in the New Testament!
The Old Testament and the New Testament
The Old Testament andThe New Testament.
If you're referring to St. Paul's letters in the New Testament, they are called epistles.
Sadducee
The New testament.