That the Son of God did the Crucifixion tells us in no uncertain terms that there is nothing He won't do for us. He has our back. Because He has our back, we can afford to take risks for the faith. We can turn the other cheek because He has our back. Our sons and brothers can become priests because God has their back. Because God has our back, we can afford to sacrifice ourselves for others. We can afford to be kind and generous because God has our back. We can love others because God has our back. None of this would be possible if God did not have our back. All of it is possible because God has our back.
How do we know? The Crucifixion tells us its so.
1) The God who made us out of the mud with His hands put Himself into the hands of the mud. Our God is humble.
2) We tortured Him but He did not stop loving us. His love for us is indestructible. The dial that controls His love for us is in his hands not ours. Moreover, it is set to the highest degree and is locked in place.
3) We killed Him but He did not stay dead. Death itself was was powerless to contain Him.
The Crucifixion is the assurance that God gave us that God has our back.