So by this logic I should thoroughly investigate every unsubstantiated claim before dismissing it. I should "keep an open mind" when it comes to leprechauns before dismissing them.
It doesn't work like that - if you make a positive claim, you show me positive physical evidence to show it exists.
Look - this is simple. IF the Christian god exists, or if ANYTHING is true for that matter, it shouldn't be difficult to PROVE IT. If I claimed I owned a car I would be able to show you that car and so on.
Christianity and leprechauns... so that is a worthy comparison in your eyes. You have testimony of those who lived at the same time as Jesus did. Thomas, a skeptic would not believe until he had physical evidence and it was presented to him. However, physical evidence isn't the only way to find truth. If you think about it, there are many things that you believe in that you have not seen. You have placed faith in things based on reason, experience etc.
Since you see Christianity at the same level as leprechauns, it should be easy for you to present an airtight case as to why it is false. So... start a thread and enlighten us all. Perhaps you will find yourself in the same quandry as Lee Strobel and Josh McDowell. They both set out to show it was false, and in the end, these highly educated men who actually INVESTIGATED the evidence (rather than making disrespectful uninformed assertions) became believers. C.S. Lewis is another skeptic with outstanding credentials and intellect who became a believer. Some of the top scientists in the world (biochemists, physicists, and astronomers) have become believers. So, let's not compare Christianity and leprechauns.
God sent his son 2000 years ago to enlighten us. He taught great things. He performed miraculous signs witnessed by many. He died on a cross and was resurrected. His followers who fled before his death (due to fear) completely changed their paths and were willing to die for what they believed in. The Bible tells us this. Historical documents other than the Bible support its teaching. His death was a payment for the wrongs of humanity. Our only way to reconcile with God is to accept the one who paid it, and accept his gift of grace.
As I said, best wishes on your pursuit of truth. Find an authority on the issue, and settle the matter. If your not ready to do that, read A Case For Christ, A Case For Faith, Mere Christianity, and Evidence that Demands a Verdict.