Actually, there is much speculation on what the fruit was all together. Apple has not been ruled out.
I could mention the historical reliability of the Bible, or point to its many fulfilled prophecies. I could appeal to the archaeological record, or the incisive way in which Jesus admonishes the hypocrites and governmental officials of his day, correcting them with a power and authority that automatically elicits my respect. I could cite the perfect teachings of Jesus, and the incredibly high standards to which he calls his followers- and the mercy he showed to those who could not uphold them.
I could point to prophetic dreams, or the many bizarre, wonderful things that have happened in my own life. I might refer to the near-death experiences of innumerable people, who have encountered a power more unimaginably strong and beautiful than they can even describe in words.
Psychologically, one might say it's because I have a deep-seated need to cling to some form of hope and ultimate purpose. Genetically- that I inherited some variation of the "God" gene. Philosophically- to reconcile the sense of wonder with which I have been gifted, to a void, nihilistic universe, devoid of the grand purpose and noble design, which my eye perceives everywhere- from the design of a humble dragon fly, to a universe that contains billions of stars, all encompassed within billions of galaxies, each composed of countless trillions of atoms, all working in concert... quantum entangled across impossible distances, in spite of astronomically mind-boggling odds.
But in reality? It is because Jesus is the only one who would ever bother to save a despicable wretch like me. No other God would have me. :P