J Scott, you want to know "Why Christianity". Couldn't you just as well have asked "Why Islam?", "Why Buddism?", "Why Hinduism?", "Why Scientology?", etc....
It all comes down to CHOICE. The only thing we are given at birth is our mother and father. After that, it is pretty much all a matter of choices. We can even chose to change our name. We chose what to wear, what to eat, whom to marry, what to drive, etc.... Some decisions are very basic, like beef or chicken for dinner or what shirt to wear. Then some decisions have a larger impact, such as what major in college, who to marry or to have children. We have a myriad of choices of what investments to make. Then there are the eternal decisions we make. And since we cannot travel beyond this life to explore and come back to make a decision, we have to go with what might be considered 'circumstantial' evidence. People who have died and were brought back within seconds or a few minutes have reported seeing something 'on the other side.' Other people have reported seeing spiritual beings during the course of their life, how much is true is any one's guess.
But if you want to know Why Christianity for me, I would say it is the sum total of my studies, my teachings, my life's experiences. I do not want to attack anyone else's beliefs, but I find gaping holes in the fundamental's in most religions. I even find gaping holes in some denominations of Christian Religions. Let me give a few simple examples. Mormon's teach that drinking anything with caffeine is wrong. Yet the Bible says that it is NOT what goes into a man that causes him to sin, but what comes out of a man, ie. his actions. Catholics believe it is ok to pray to dead saints and others. Yet Jesus states very clearly in the Bible that you are to pray to NO ONE but God. Baptist's believe that once you are saved you cannot lose your salvation but the Bible clearly states that God can erase your name from the Lamb's book of life. The faith I was brought up in states that drinking alcoholic beverages is a sin yet Jesus turned water into Wine. I don't think Jesus would make an item of sin.
The problem with God's plan is that man keeps getting involved for his own end and own benefit. Every religion on earth is MAN MADE.
Jesus being born, walking the earth, being crucified and then raising from the dead three days later is extremely well documented, both in religious and secular writing. The Roman Historian, Josephus, writes very clearly of these events. His coming was well documented in prophesitical writings that are verifiably thousands of years older than his birth. No other so called religious leader, whether Mohammed, Buddah, or even Joe Smith, has as much irrefutable evidence as to their deity than Jesus Christ.
Why Christianity? It's my choice.