Because without it, we have no basis for belief. Anyone can justify belief in anything without any possibility of scrutiny. This frightens me. Faith and revelation are inscrutable under your position, and that makes them prime candidates for manipulation and abuse. Let alone the fact that there is good reason to conclude that faith and revelation will NOT lead you to a reliable conclusion (the mere presence of faith guiding you to two contradictory positions with no way of deciding between them proves this).
Sarcasm aside, you offer nothing more to the debate than the people who argue "I believe on faith and there is nothing you can say to convince me otherwise".So, comrades - we have found the Truth! Lay aside your idols, for there's naught but one true idol! That idol is called Man, and He alone is worthy of His own worship! May we fast spread our creed to the four corners of the globe so that Man may attain enlightenment under the guise of a new Religion - free from ancient superstitions!
I must show your people the Truth, Lord. I must!
Lol.
Those of us who value the search for truth (even if it is unattainable), or even non-contradictory theories of evidence, will dismiss faith as a system of justification.
Because you do not justify your claim of truth at all. Inscrutable "revelation" is all that is necessary for a claim of truth on your position.Edit - Don't be mistaken. Secular Humanism and Atheism are great, very intelligent and very constructive. They are also very sane and very clear minded. It might be the best for many to stay as such. BUT I don't feel obliged to consider them as "truth".
How about this: it was just revealed to me that an green apple is floating in the middle of the Andromeda galaxy... By your own argument that belief is now unassailable. You can no longer argue my irrationality because my justification is revelation.