"Wasn't [the New Testament] written
like 300 years after Jesus?"
No, the New Testament wasn't written 300 years after Jesus.
You may be referring to 325 AD, when the Council of Nicaea officially
recognized the New Testament as
having been written by God. But by then, Christians had been
reading the New Testament as God's Word already for two centuries.
So when was the New Testament
Please pay close attention to the dates below:
Acts, the fifth book in the New Testament,
is a methodical account of the early church
written by a doctor named Luke when he was the assistant to and the note taker for
the Apostle Paul.
62 AD was when Paul was martyred in Rome. 64 AD was when Emperor Nero burnt Rome
and blamed the fire on Christians to launch the Roman persecution of Christians,
and 70 AD was when the future Emperor Titus sacked Jerusalem; both were major
milestones in the history of early Christianity.
If a historical account of New York City mentions the the construction and the
presence of the twin towers of the World Trade Center but ends without
mentioning their destruction, that historical account predates September 11,
2001. This conclusion is warranted, isn't it?
Acts ends without mentioning the sacking of Jerusalem in 70 AD; this indicates
that Acts predates 70 AD.
Acts also ends without mentioning the great fire in Rome and the ensuing Roman
persecution of Christians across the Roman empire; this indicates that Acts also
predates 64 AD.
Acts ends just after mentioning Paul's completion of his 2 year imprisonment in
Rome but without mentioning his martyrdom in 62 AD. This indicates that Acts was
completed in 62 AD.
Luke begins Acts with:
"The former account I made, O Theophilus, of all that
Jesus began both to do and teach..." (Acts 1:1)
“former account” Luke referred to was what we call
today the Gospel of Luke, which was also written by Luke to this man named Theophilus:
"Inasmuch as many
have taken in hand to set in order a narrative of those things which have
been fulfilled among us, just as those who from the beginning were
eyewitnesses and ministers of the word delivered them to us, it seemed good
to me also, having had perfect understanding of all things from the very
first, to write to you an orderly account, most excellent
you may know the certainty of those things in which you were instructed."
The delivered eyewitness accounts Luke mentions above are the
Gospel of Matthew, written by one of Jesus' 12 Apostles, and the Gospel
of Mark, written by the note taker for Apostle Peter.
Estimating 3-5 years between Acts and Luke, and another 3-5 years
between Luke and Matthew & Mark dates three of the four Gospels to 52-59 AD,
which is only 2 decades after Jesus'
Some of the other New Testament books were written before and some after
these Gospels, but all were written by eyewitnesses of Jesus or their note takers,
and read by people who were also eyewitnesses and could validate