He was crucified to demonstrate to His disciples the ultimate gift of love:
"This is my commandment, That ye love one another, as I have loved you. Greater love hath no man than this, that a man lay down his life for his friends." Jn 15:12,13
His true disciples were expected to do the same, whether called upon to do so literally, or figuratively (to give in the name of love, if necessary).
The crucifixion was not meant to be an atoning sacrifice through blood ... According to Law, if animals could not be offered, fine flour could be offered (Lev 5:11); therefore blood was not absolutely needed for the remission of sins, as Paul would like to require.
In fact, the cup that he drank from during Passover was what Jesus specifically identified as the blood shed for the remission of sins (Mt 26:28), not His crucifixion. The cup (ποτήριον
, represents "one's lot in life, whether good or bad". When Jesus drank the cup, and commanded that His disciples share in it, it symbolized that the true disciples would share in Jesus' lot in life ... His walk, His sufferings and, soon, His blessings. This was the true blood (blood being life) shed that produced remission of sins ... to walk in righteousness with Him. In summary, the blood & life we shed for Him through participating in His walk, trials, temptations, sufferings is for the remission of our sins, and we will inherit the same blessings He inherits, such as eternal life.