Now we know that Christ went to the cross so He could demonstrate His love:
“In this was manifested the love of God toward us, because that God sent his only begotten Son into the world, that we might live through him.” (1 John 4:9)
Judicially, it wasn’t necessary for Christ to go to the cross, but He endured suffered a second time out of love to demonstrate to the elect what He had already done for them before time began.

We find this reiterated in First Peter where we are told Christ was already the Lamb slain before time began, but He did it again “in these last times for you”:
“But with the precious blood of Christ, as of a lamb without blemish and without spot: Who verily was foreordained before the foundation of the world, but was manifest in these last times for you” (1 Peter 1:19-20)

A logical question at this point is, “If Christ already made the payment before this world was created, then why did He go to the cross?” Christ had already made the payment for sin prior to Creation, so from a judicial standpoint there was no need for Christ to go to the cross. This is why God recorded that no sin was found in Christ:
“Then said Pilate to the chief priests and to the people, I find no fault in this man.” (Luke 23:4)
In the past we’ve always understood this to be stating the obvious: Jesus Himself never sinned. We would say He was carrying our sins, but He Himself was without sin. However, now we can better understand why God put this in the Bible. True, Jesus Himself was without sin, but at that point He wasn’t carrying the elect’s sins either because they had already been paid for before Creation.