"Wasn't [the New Testament] written like 300 years after Jesus?"
No, the New Testament wasn't written 300 years after Jesus.
You're probably referring to 325 AD, when the Council of Nicea officially
recognized the New Testament as having been written by God. By then, Christians had known and been
reading the New Testament as God's Word already for 200 years.
Please pay close attention to the dates below on when the New Testament was
written:
Acts, the fifth book in the New Testament, is a methodical account of the early church
that was written
by a doctor named Luke when he served as the assistant to and the note taker for
the Apostle Paul.
62 AD was when Paul was martyred in Rome. 64 AD was when the Emperor Nero burnt
Rome and blamed the fire on Christians to launch the Roman persecution of
Christians. 70 AD was when the then general and future emperor Titus sacked
Jerusalem.
When Luke ends Acts, Paul had just arrived in Rome to start his 2-year
imprisonment prior to his execution. Acts ends without mentioning any of the
major events above, which indicates that it was writte
n around 60 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) The
“former account” Luke referred to was what we call
today the Gospel of Luke, which was also writte
n 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
Theophilus, that
you may know the certainty of those things in which you were instructed."
(Luke 1:1-4)
The delivered eyewitness accounts Luke mentions above are the
Gospel of Matthew, writte
n by one of Jesus' twelve Apostles, and the Gospel
of Mark, writte
n by the note taker for the 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 50-57 AD,
which is only about 20 years after
Jesus'
ascension.
Some of the other Ne
w Testamen
t books were writte
n before and some after
these Gospels, but all were writ
ten by eyewitnesses of Jesus or their note takers, and read by people who were also eyewitnesses and could validate
their details.