
I am asking you to believe in things not visible. I don't know if this is
believeing blindly or not. I'm not sure how blindness comes into it. I do
not deny reason, indeed I insist upon it, but reason only draws conclusions
from evidence. If you decide in advance that your reason will act only on
the evidence of the five physical senses, then you cut reason off from any
possibility of reaching a conclusion outside the physical sphere (beyond the
rather provocative, if inconclusive, conclusion that the physical sphere
is not self explanatory). 

Christians claim that they have received a different kind of evidence, 
which they call faith, and which is a gift of God. That is, this evidence
is the evidence of a thing which chooses to reveal or hide itself. The 
evidence of the senses cannot tell you is such a ting exists. Reasoning
on the evidence of the senses won't help either. But Christians do reason
of the evidence of faith, and do claim that this evidence is wholly
consistent with the evidence of the other senses, and indeed, that the
evidence of these other senses is part of God's revelation of himself
to us.

It is not necessarilly the case however that knowledge of a God must come
through this route. There may be other senses than the physical ones
providing evidence of non-physical realities. (There may, of course, be
physical realities of a type for which we have no corresponding senses, for
all we know.) These senses, if they exist, may provide valid evidence for
reason to work on. And, as with all senses, these senses may be impaired
in some people, that is, they may be spiritually blind. In this sense,
belief in God becomes an act of sight, and it is disbelief which is blind.

Faith, as I have said, is not opposed to reason, it is simply a new source 
of evidence on which reason may operate. It is clear that human beings
have many systems for explaining the evidence of the physical senses, and
similarly there are many systems for explaining the evidence provided by
faith. Religious believers in general, and Christians in particular, use
reason to help sift through the evidence to come to a clearer understanding
of the evidence provided by faith. Science claims, with good reason, to be
the most valid system for explaining the physical universe, and Christianity
claims, also with good reason, to be the most valid system, possessed of the
best evidence, for explaining Gods revelations of himself to man.

If you doubt that Christians use reason, read this newsgroup for a while
and you will see rational debate aplenty.