Jesus obedience that made us righteous was the death of the cross.
And just as Christ was said to outdo Adam's destruction in
Romans 5, it affects us by being baptized into the death of Jesus according to the very next chapter 6.
His sinless sacrifice was necessary for us to be deemed dead through His death and righteous in Him. So the cross is the only way for God to save anyone. And without the cross Jesus did not have to SUFFER LIKE HE DID so terribly.
If God has another way apart form the cross to save someone, do you think he would go through with all of that suffering? Everyone could go without the cross IF ONE PERSON CAN.
Every other way is salvation by works. We are saved by some good we do, and not the good Christ did on the cross.