—Faith is choosing to believe a particular truth claim as fact, even though the supporting evidence for that claim is weak to non-existent.—
Would anyone ask you to believe a truth claim, by faith, if the evidence for that claim is overwhelming? I don’t think so. Claims with overwhelming or even just strong evidence do not require “faith”.
Therefore, in my opinion, the fact that Christianity asks you to believe in Jesus as your Lord and Savior “by faith” is an admission that the evidence for the core claims of Christianity are weak to non-existent.
Here is a definition of “faith” used on the atheist blog, “Debunking Christianity”.
—Assigning a degree of certainty to a claim beyond what the evidence suggests is reasonable.—
I like this definition. Of course, Christians will want to argue that faith IS reasonable. They will also come back and say that the existence of a Creator God increases the “reasonableness” of a (biblical) claim. My definition is only based on the evidence for the claim itself not on what is “reasonable” in an undefined sense of that word.
How about this revision of my original definition:
—Faith is choosing to believe a particular truth claim when the evidence for that claim is not strong enough for most rational people to believe it on its own merit.—
I have debated numerous Christians who when confronted with the weak evidence for the Resurrection of Jesus will respond with: “Jesus didn’t make the evidence strong because he wants you to believe in him by faith.”