There Could Be No Redemption for Mankind Save it Were Through the Death and Suffering of Christ and the Atonement of His Blood

Aaron, a Nephite missionary, teaches that…

“…There could be no redemption for mankind save it were through the death and suffering of Christ, and the atonement of his blood.” (Alma 21:9)

Questions:

-Does God redeem His children (mankind) outside of the demands of justice?

-Was there any other way to satisfy the demands of justice, while still showing mercy, without God providing an atoning Savior?