I've been thinking recently about different Bible doctrines that are confirmed and proven by a consideration of the cross of Christ.
The deity of the Lord Jesus is confirmed by the cross. This is seen in the fact that had the Lord Jesus been anything less than God He could not have paid the infinite penalty for sin. Furthermore, had the Lord Jesus been less than God then His substitutionary work could only have been a "one for one" thing. The fact that He gave Himself on behalf of all, and all who believe can claim Him as Substitute shows that He must be God. This is why the Lord said to those in John 8 v 24 "If you do not believe that I am, you will die in your sins" ("I am" is a title of God.) Those who deny the deity of Christ have no Saviour, because none less than God could satisfy the claims of God against sin and provide salvation for the world.
The true humanity of the Lord Jesus is confirmed by the cross, because only a real man could suffer and die (Hebrews 2 v 9). And the Lord had to be human in order to take the place of humans. So if the Lord was not really human He could not take our place, but, as we saw above, if the Lord was only merely human He could not take our place, and thus the Word who is God became flesh (John 1 v 1, 14).
Eternal punishment is established by the cross. You may wonder how so. Look at what was happening at Calvary, the Lord Jesus entered into darkness in which He was banished from God (Matthew 27 v 45-46) and punished by God (Isaiah 53 v 5-6, 10; 1 Peter 2 v 24), and He suffered this in His soul and body. But He emerged from the darkness and said "It is finished!" (John 19 v 30). Then He, by a deliberate act of His own will, dismissed His spirit and died. What the Lord Jesus experienced prior to His death is exactly analogous to what the unbeliever will experience in the Lake of Fire - the lost soul will enter darkness, will be banished from God and punished by God, but because the lost soul is a finite being he will never be able to do what Christ did - he will never come out of the darkness and say "It is finished!" Only an infinite Person could do that. (Some might wonder then why He physically died, but if sin is to be fully atoned for then all the consequences had to be borne by Christ, and thus He had to physically die in order for man to be reconciled to God and death to be defeated. We could say accurately that He bore the horrors of the second death (i.e. the wrath of God against sin - Revelation 21 v 8) prior to experiencing the first death.)
The love of God is proven at Calvary. This is the supreme proof of God's love (Romans 5 v 1-8), and the unchanging assurance that God is for us (Romans 8 v 31-32). We know that God loves us, not because life goes well, but because God gave His only begotten Son (John 3 v 16).
The righteousness of God is seen at the cross - God has not passed over sin, or brushed it under the carpet - sin's penalty has been paid, and divine justice satisfied. He is not like the false gods of every other religion, He doesn't show mercy at the expense of justice - He is just and the justifier of him that believes on Jesus (Romans 3 v 21-26).
The wisdom of God is displayed in the death of Christ, because only a God of infinite wisdom could have such a plan. Indeed, it is the wisdom of God that thrilled Paul so much as he considered the Gospel message (Romans 16 v 27).
The exclusivity of salvation through Christ alone is seen at the cross - if there had been any other way for sinners to be saved do you think God would have given His Son? See Matthew 26 v 38-42; Galatians 2 v 21 - when we hear the words, "My God, My God, why...?" and see the bruised, marred, scarred form of God's Son on the cross, we realise there is no other way to be saved other than through Christ and His cross. If there had have been, God would have taken it.
There are many many other things we could mention, but that will do for now. If you want to know what God is like, view Him in the shadow of the cross.
