It is not good enough to just to believe God exists because even some people who hate God believe that. Nor can we think a moral life is enough, for as Jesus said “no-one is good but God alone.”
Christianity is about enjoying a relationship with God through his Son Jesus. To enter this relationship we need to receive God’s forgiveness, and to receive this we need to trust Jesus for it. Only he can give us God’s forgiveness because he is the only one who will judge us for how we’ve lived, because he is the only one who bore the punishment for sin in his death so that we might not have to experience it, and because he is the source of life itself.Being a Christian is therefore about more than believing in God. It is to believe that Jesus is God’s Son and ruler, and that he is willing and able to forgive those who come to him. It is therefore also about more than being good. The Christian lives a good life not to earn God’s forgiveness or deserve a place in heaven, but because they trust Jesus, want to please him, and know that he knows the best way to live.
Jesus was adamant that anyone who truly knew God would respond to him in these ways.
(John 3:16-21, John 8:31-47, Acts 2:42-43)