Here is one of the most profound and concise arguments on the significance of the historical accuracy and supernatural nature of the events in the Gospel accounts, and how it relates to the gospel message.
“Other religions are primarily philosophies. That is, they are sets of teaching about how to live. Christianity is primarily an announcement of events in history, things that happened. Those events include the incarnation (God becoming a human being), the crucifixion (the God-man dying in our place), and the resurrection (the God-man breaking death so he can live with us and us with him).
Other religions have accounts of miracles, but they only authenticate or exemplify the founders’ teaching. But whether the miracles happened or not does not ultimately make any difference, because it is the following of the teaching that saves us. But in the Christian faith, we are saved by grace, not our performance. We are saved not by what we do but what he has done. Therefore, it is the miraculous events which actually save us. We’re saved NOT by the teaching, but by these historical events.
Thus, if you take away the historical events of Christ’s life and death and resurrection, you take away the heart of Christianity, and it becomes just another life-philosophy that saves you through your own self-effort.”
From Redeemer’s study on Mark.