The Cross is the most important symbol of Christianity.
It tells the story of Jesus Christ who lived 2000 years in what is now modern day Israel. He was arrested, falsely accused, and sentenced to death. He was mocked. A crown of thorns was placed on his head, he was nailed to a wooden cross and left to die in agony.
Christians believe that Jesus chose to die for us. He lived a perfect life. He loved his Father God and he loved us. He gave his life for us, and took onto himself our sin: our self-centredness, envy, jealousy, arrogant pride, self-justification, evil desires, hatred and cruelty. And because he died for us, because he went to hell for us, if we put our trust in Jesus we are forgiven and put right with God. We can know God as our Father in heaven and we can know Jesus Christ, the Son of God, as our friend.
The death of Jesus on the cross means that we can look at ourselves very honestly and see all the evil that is in our heart, and yet know that we are deeply beloved and forgiven.