The reasons why I believe in Christianity:
1. The evidence, its very very strong currently and continues to get stronger with each passing year. As from what I can see, the biggest challenges to Christianity from atheism and other religions is less than impressive. Atheist challenges like darwinian evolution, the multiverse, origin of life models one are not standing up well under cross examination and even if any or all these things were proven true they would not by any means, disprove Christian theism. Christian theism can fully stand even in the light that all these things were proven true.
On the contrary the evidence currently indicates that the universe had a beginning just like the Bible predicts. Meanwhile life in the universe appears to be rare and what little life there is (which most if not all is on this one planet) is extremely complex and complicated and when argued from atheist positions as coming from cold and dead matter all by itself over eons of time just does not hold up against the evidence nor to common sense. After all, how does the impersonal of carbon atoms, oxygen atoms, hydrogen atoms and other particles give rise to the complex personal thinking minds of human beings?
Also, challenges against the resurrection of Christ have failed greatly. Theories like the swoon theory, wrong tomb theory, the disciples stealing the body to name a few don't hold up to cross examination and have thoroughly disproved by theologians, archeologists, medical doctors and philosophers.
If you like what I once was, confused about all the different religions out there in competition with Christianity take note that in the entire history of humanity has no religion stood the test of time, the test of trials, the test of hostile scrutiny that Christianity has and continued to not only endure but thrive. Unlike Buddhism, Hinduism, Mormonism and Jehovah's witness (to name a few) which are thoroughly discredited and disproved to be true, even among the harshest critics, Christianity stands up way better than any religion.
Not only the top religion that stands up to the most scrutiny it also has accomplished the most good than any other religion, view, political regime, philosophy ever in human history. Other religions like Islam which rule by bloodshed, terror, and force, Christiany's core teachings involve love, forgiveness, humility and grace.
2. Purpose in my life and in everyone's life
A major advantage on what my relationship with Christ does for me is it gives me a deep sense of purpose. It satisfies all of my deepest intellectual and emotional needs.
After I through, sincerely and as non biased as possible, compared all the truth claims from all of the mainstream and non mainstream religions along with how well their claims stand up against archeology, science, philosophy and how well they satisfy the deepest needs of human beings, like most you should narrow your options down to two, Christian theism and naturalism/atheism.
Clearly, from a personal standpoint I don't see how I can face everyday without knowing I have a deep, real, and honest reason for living. I also feel extremely uncomfortable with the truth that if God (especially the Christian God) does not exist than there are no real objective moral values. Under those circumstances moral values are retaliative at best.
That along with the fact that if God (especially the Christian God) does not exist then for me especially there is no real purpose for living and so called "things" that most people value like love, freedom, friends, family, career and so on, in the grand scheme of things if the Christian God is not real are all completely worthless! Sure things like these may have "meaning" to us right now, but consider this, even if our "meaning" is passed down from generation to generation through our children or if we build huge monuments from steel, stone, or any other durable material that last thousands and perhaps even millions of years once humanity ends here on earth at the very least (if indeed the Christian God is not real) then everything that everyone holds meaningful and every memory or indication that we were once here will be forever destroyed.
I also am very sure that this would also apply to any other intelligent life that's in the universe (though we have not found any to date) and to even other "universes" within a multiverse. Entropy will have the last victory if the Christian God doesn't not exist.
Now possibly the Christian God and all the other known gods throughout time are all false but maybe we are governed by some other kind of god whom man has never met or has any record of, most would call this some sort of deistic god.
But since we don't know or would ever know about this god in our lifetimes and because of all the positive evidence we have for the Christian God being real compels me as it should you, to put your faith in Christ.
3. Plan of salvation
As many people know but others are confused about, here in the best way I can explain it, is God's plan of salvation for us. As human beings we are all sinners and have fallen short of God's glory.
This all started with Adam and Eve's first sins in the Garden of Eden. Since then every human being born from Adam's line is a sinner. And sadly for us, human beings if they die in their natural state, they end up in a place of constant fiery torment call hell, a place meant for satan and his demons.
But God has a plan to redeem mankind from having to experience such a fate. God who is one but in three persons (Father, Son and Holy Spirit) sent His Son, Jesus into the world alittle over two thousand years ago to be that sacrifice for the world's sin. Because before Christ came into the world people had to kill or shed blood of an animal (namely lambs) every so often to temporarily forgive them for their sins. But because that wasn't a final enough and Holy enough sacrifice, God the Father sent His Son Jesus to finally offer that final and Holy sacrifice for man's sin.
Therefore all a person has to do in order to make it into God's kingdom is to believe that Christ is the Son of God, repent of your sins, and trust in Christ for your salvation.
Many people start their relationship with Christ with a prayer, others like back in the time of the early church began with baptism, but as long as you make that commitment to truly believe and accept Christ's sacrifice, you are His. Then not as a requirement but as acts of love, try to follow Christ commands of loving God with all your heart, soul, and mind, and love other people (even your enemies) as yourself.
Now granted, even as a Christian you will still sin, and make mistakes, all the way until death, but Christ prayed for all your sins, past, present and future sins. But anytime you do, you should confess it to Him and ask Him to help you keep from committing those sins in the future. Again, this is all out of love, good works do not save you, but they are a indication to you and to others, that you truly love and trust Christ.
After making your initial commitment to follow Christ it is highly recommended that you, pray and talk with God on a frequent basis, read the Bible, get baptized and join a good Bible believing church. And then try to find ways to either serve the church or serve God through any kind of way that you feel led to do.