As Christians we believe that God is uniquely revealed in the Bible which is a collection of books written over hundreds of years. We understand that God is difficult to describe in human language but use words like "goodness", "love" and "power" to and beyond the greatest meaning we can give them. Through the Bible we learn the history of God's relationship with humanity and human responses in praise, poetry and song and, sadly, the consequences of the times people ignored him. The Bible tells us of the conditions of our relationship with God and how we should be able to respond to his great love with love and obedience. Through our understanding of what the Bible shows of these conditions we also become aware of when we have failed to live up to them - when we are selfish, unloving or deliberately disobedient to what we know is right in God's eyes; these are the occasions we call "sin" and they spoil the relationship with God and distance us from him.
We understand that our earthly life from birth to death is only the start of our life and we continue to exist beyond death. Our earthly life gives us the opportunity to decide our fate beyond death - either to live in God's love (commonly referred to as "heaven" or "eternal life") or to live without God's love (commonly referred to as "hell" or "second death"). Sin, however, prevents us from continuing to live in God's love beyond death.
The Bible points out that, by our own efforts, human beings are unable to live without sin and would therefore be destined to miss out on eternal life. However, God's plan was always that we could live in eternal life so he sent Jesus as the older books in the Bible (the "Old Testament") had predicted.
Jesus lived in what we now call Palestine/Israel between 4 BC and AD 29 - and we celebrate his birth at Christmas. As well as the four accounts of his life in the Bible (the Gospels) he is mentioned in the writing of the Jewish/Roman historian Josephus, who lived shortly after Jesus died. From about the age of thirty Jesus gathered a small group of followers (disciples) and taught that God's way is one of selfless love and that the kingdom of heaven is open to everyone. You will also hear Jesus referred to as "Christ" or "Son of God" - among many other titles; these titles are an attempt to describe how Jesus could be fully human - just like us - and also God. We use the word "incarnation" (often at Christmas) in an attempt to understand that when we refer to Jesus we are seeing God in human form.
At the Jewish festival of Passover in AD 29 Jesus was arrested - although he had not committed any crime. He was tried in an illegal court and sentenced to death. He was executed by the Roman authorities, in their customary barbaric manner, by being nailed to a cross (crucifixion) and left to die as his internal organs failed. As a human being, Jesus' death was genuine and painful. After he died, one of his followers who was wealthy let Jesus' body be placed in a rock grave which he had prepared for himself.
We understand that sin prevents us from from entering eternal life; Jesus, however, had never sinned - meaning he could not remain subject to death (or second death). On the third day after his crucifixion Jesus came back to life - "rose" from death - and was seen by many who had previously been close to him. Many people have tried to explain why Jesus' body is no longer in the grave he was placed in, but it is the most central understanding of the Christian faith that Jesus' dead body was placed in the grave after his crucifixion and three days later he was alive again (the "resurrection").
Jesus' death and resurrection are not just historical events from nearly two thousand years ago - they affect us today. Jesus had no sin at all - we, sadly, sin every day; in the natural course of events this would mean no prospect of eternal life in God's love after our own death. Yet, Jesus volunteered to take the blame for our sin on himself as he died - effectively leaving us free from sin and able to enter eternal life. This is available to everyone - all we need to do is recognise the sacrifice Jesus made for us and resolve to live the rest of our lives subject to his lordship.