In what sense is it said that Jesus Christ was crucified “for us?”
The Lord’s death on the cross, his sacrifice offered to the Most High as our great High Priest, has a purpose: by his death to deliver us from sin, the curse, and death. As St Paul writes:
In him all the fullness was pleased to dwell, and through him to reconcile all things to himself, both earthly and heavenly, having made peace through the blood of his cross. In the past, you were alienated and hostile in mind in your evil actions; but now he has reconciled you in the body of his flesh through death, in order to present you holy, without blemish and blameless before him, if indeed you continue in the faith, grounded and steadfast. (Col 1:19–23)