At some point, Christianity is a matter of faith. Faith is believing in something just beyond your ability to physically see. However, believing in Christianity is not as much of a leap of faith that some think it is. Christianity makes logical sense. Below are resources to show that Christianity is true from Norman Geisler.
1- Truth about reality is knowable.
2- The opposite of true is false.
3- It is true that the theistic God exists.
4- If God exists then miracles are possible.
5- Miracles can be used to confirm a message from God.
6- The New Testament is historically reliable.
7- The New Testament says Jesus claimed to be God.
8- Jesus' claim to be God was miraculously confirmed by:
- His fulfillment of many prophecies about Himself;
- His sinless and miraculous life;
- His prediction and accomplishment of His resurrection
9- Therefore, Jesus is God.
10- Whatever Jesus (who is God) teaches is true.
11- Jesus taught that the Bible is the Word of God.
12- Therefore, it is true that the Bible is the Word of God (and anything opposed to it is false).