Is "you must have faith" an argument used by Christians when they cannot back their claims with logic?

Yes, I see it time and time again. Any time a religious person (not just christians) think they have a valid argument for their god or gods, they present it, after they're shown the facts anf fallacies they continue to try to defend it until there's absolutely no hope, then they just say "Well you just have to have faith". Well done, you've just shown me that I'm victorious. The faith line is a cue to surrender, and it admits that it doesn't apply for people who don't have faith, and therefore was never logical at any point since logical arguments have to apply to everyone and not just people of faith.

So tell me... have you, personally, with your own eyes, ever seen actual proof of evolution, dark matter, the big bang, black holes or the expanding universe? Have you personally seen, first-hand, dinosaur bones being dug from the ground? Have you personally seen a hole deep enough to see the molten iron core of the earth? Have you peered onto the lunar surface with your own eyes and witnessed a flag, a footprint or the portion of the lunar module we left there? Have you sampled the sun and tested to see what gases it contains? Have you measured the distance between planets for yourself? Or have you simply accepted these things as fact based on the words of other people who claim to know? I'm betting it’s the latter. You’re believing in what someone else says, without the need to verify any of it for yourself. This is faith. You have faith in the scientific community. So much faith, in fact, that you are willing to attack someone else’s faith without provocation or proof of the contrary. When someone questions science, and you say “well scientists have seen evidence…” you are basically saying that you believe these scientists without question, which is exactly like saying… “you must have faith”. Funny thing about truth and proof versus faith is that we can argue to the point of saying “nothing” can be proven. For example… prove to me that you exist. Seems simple enough. We’re conversing, so obviously you must exist. But schizophrenics converse with non-existent people all the time. Who’s to say I haven’t created this entire world within my own mind? Who’s to say my friends, family, you, and even this website aren’t figments of my very sick mind? For that matter, who’s to say we’re not all figments of yours. See my point? Faith is nothing more than a belief without proof. There is no proof of human evolution, that’s why we call it a “theory”. There is no proof of the big bang, that’s why we call it a “theory”. Scientific minds have “faith” in these things (Don’t ever confuse “evidence” with “proof”. They’re not the same thing). Do a little research into the multiverse theory. Multiple parallel universes coexisting with our own. Parallel universes! Altered realities! Research string theory, superstring theory, or M-theory, or better yet, Loop Quantum Gravity. Do some research on dark matter… there is vastly more gravity in the universe than can be accounted for by mass, so Zwicky thought up dark matter to account for this missing mass creating all that gravity. It’s a commonly believed theory, but it is only that, a “theory”. So when you tell me that I should believe in non-existent mass, parallel universes, quantum gravity, or that everything exists because there are invisible vibrating strings everywhere… I should just take your word for it. But when someone tells me there is an other-worldly being that created everything, I simply tell them it’s illogical? Your argument is illogical. Why is one crazy, improvable notion easier to believe than another crazy, improvable notion? Because a group of guys in lab coats told you it was true? C’mon…

yep.

"Faith and logic are two sides of a coin"

Atheists have faith that the universe sprang out of nothing, even though it violates the first rule of classic physics... cause/reaction. Atheists have faith that the genetic code sprang out of nothing, even though it violates the first rule of information theory... all codes have authors. They cannot back up either of these claims with "logic". Atheists require a few free miracles to base their faith in Atheism upon.

Some Christians demonstrate their lack of faith in Jesus when you try this sneaky little trick.. Ask the guy -supposing Jesus approached you to say that Satan will release 2 sinners from hell if you can be willing to take their place. After some mental anguish (one Christian guy I asked this Q. almost started crying) the guy always says 'no'. So I say to him 'where is your faith in Jesus; don't you think he'd have a plan to rescue you before he ever approached you with such a question?'

Yes.. its used just after they dribble on with a quote from a book of myths

One must have some faith, not just in religion but - things like yourself etc etc

Cool, explain to me how modern humans "evolved" in such a short time? It's estimated that modern humans appeared 300,000 years ago. Other "man apes" existed for about 600,000 years. Miraculously, modern humans appeared within 100,000 years of "man apes". Far too short for evolution to have taken place. No transition fossils of manape to human (missing link) have ever been found. As a matter of fact, no transitional fossils of any kind have ever been found. What else is evolution but "faith" that Darwin and atheists are right?