The Christian perception of the cross as a sign of redemption stems from the belief that Jesus' Crucifixion played a central role in redeeming humanity from its sins. When Jesus was crucified, the cross became a symbol of suffering. Then with the resurrection of Christ, the Christians saw it as a symbol of Jesus' victory over death.
During the first 300 years after Christ's death, Christians feared persecution by the hostile Roman government and rarely displayed the cross in public. In the 300's, the Romans began to tolerate Christianity, and crosses were widely displayed. In A.D. 325, Constantine at the Council of Nicaea issued a decree that the Cross is the official symbol of Christianity.
On Good Friday, the cross is covered with black, a color for mourning for the death of Jesus. Before the Easter Sunday, the draping in black is removed and the cross is rather decorated with flowers to honor the Jesus' return to life.
