The God Man That Knew No Sin
For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God.
2 Corinthians 5; 21,

The cross to the Christian is a symbol where their sins are, and they/re forgiven by Christ, and declared righteous before Jesus Father. And God grants and credits to us, the perfect satisfaction, righteousness, and holiness of Christ, as if I had never sinned nor were a sinner,
For Jesus, it was the ultimate sacrifice a place of extreme suffering and agony. Where every sin that man committed fell upon Him, and His beloved Father who loves him dearly forsakes Him, because of our sins.
The similarity between the fallen solider and Jesus is that they were both innocent, and dies because someone else lack of judgement. In Jesus case He committed no sin, yet he was sacrifice for our sins as Caiaphas stated, that one man should die for the people rather than the whole nation perish.” He was willing die to take our place, He obeyed His Father, and went to the cross, to suffered a shameful death. He went to the cross to shed His blood for our sins. He went to the cross to set us free from our sins.
In both cases, the cross symbolizes the sacrifice they willing to make for our sake.