The early church fathers taught that man would only have 6 thousand years
because unlike Christians of today they were familiar with the Book of Enoch
and the Secrets of Enoch.  Neither of these were canonized at the council of
Laodicea, but I have read them and God flat out tells Enoch that man only
has six thousand years on the earth.  What I also find interesting is that
the Angels that took Enoch into heaven introduced him to Jesus in heaven but
he was just known as the "Son of Man whom unto all righteousness is given".
I am convinced that is why God despises the Laodiceans, because they chose
what we could read about the Lord and what we couldn't.