This is the question that I will be investigating on this blog site for the next four or five years.
Before I go into specific arguments for or against some key Christian beliefs, I will first discuss a preliminary question (in 2016):
What is Christianity?
1. Does God exist? (investigation targeted to complete in 2017)
2. Did Jesus exist? (investigation targeted to complete in 2018)
3. Did Jesus rise from the dead? (investigation targeted to complete in 2019)
4. Was Jesus God? (investigation targeted to complete in 2020)
The following diagram shows how these questions are related to the larger question "Is Christianity true?" (click on the image below for a clearer view of the diagram) :
If the answer to any one of these questions is "No" (or "probably not"), then the Christian faith is false (or is probably false).
If the answer to all four of these questions is "Yes", then Christianity might be true.
The Christian faith includes more than just the beliefs that God exists, that Jesus existed, that Jesus rose from the dead, and that Jesus was God incarnate. For example, the Christian faith also includes the belief that human beings are sinful and in need of God's forgiveness, and that the death of Jesus provides a way for humans to be forgiven and to be reconciled with God, and that faith in Jesus as the risen lord and savior of humankind is the key to being forgiven and reconciled with God, and to obtaining an eternal life of happiness.
Thus, even if the Christian beliefs concerning the above four key questions are all true, it could still be the case that Christianity is false (or probably false), if other key Christian beliefs turned out to be false (or probably false).