He doesn't contradict himself.  The church is to last for all time.
However, there are those who use the church to bolster themselves.  This
is evident in many letters.  For instance, Paul talks about the
"super-apostles" to the Corinthians (2 Corinthians 11-12), he mentions
how people will be led away by miracles, signs, and wonders (2
Thessalonians 2:9-12), he tells Timothy that it is clear that some will
abandon the faith and teach lies (1 Timothy 4:1-3) and that some will
search for teachers to suit what they want to hear (2 Timothy 4:3-4).
Such passages go throughout the letters and Jesus does warn about them
(Matthew 24:4-14).  But look at the promise in this last part.  Verse
14:  "And this gospel of the kingdom will be preached in the whole world
as a testimony to all nations, and then the end will come."  Even today,
there are false teachings.  I can name two which I am well familiar
with:  the non-need of baptism and the "praying of Jesus into your life
for salvation".  Both are taught.  Both are DEAD wrong.  They have been
taken out of context from some verses, interpreted from others, and just
plain made up.  The ONLY way Jesus taught is given in Luke 9:23-26 and
Luke 14:25-33.  He then commands baptism in Matthew 28:18-20.  The
church Jesus founded, though, is alive and well.  It's not being
persecuted as much as back then (the laws won't allow it yet), but it is
being persecuted.

Joe Fisher