One of the most critical days in the history of this universe is when God gives Himself for the sake of the sins of humanity. Some 2000 years ago, Jesus Christ, the Son of God, who is God Himself, gave His precious, sinless life for the redemption of humanity. Does He have any need to die for the sake of sinful beings? No. However, this demonstrates His unconditional love - "God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life." (John 3:16).
On this day, the Christian world observes Good Friday - the day Jesus was put to death. However, no one put Him to death because no one has the power to kill Him; He gave His life.