Heidelberg Catechism · 1563

Q67. Are both the Word and the sacraments then intended to focus our faith on the sacrifice of Jesus Christ on the cross as the only ground of our salvation?

Yes, indeed. The Holy Spirit teaches us in the gospel and assures us by the sacraments that our entire salvation rests on Christ's one sacrifice for us on the cross.
Answer · Heidelberg Catechism

Scripture proofs

  1. [1]
    Romans 6:3

    Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death?

    1 Corinthians 11:26

    For as often as ye eat this bread, and drink this cup, ye do shew the Lord’s death till he come.

    Galatians 3:27

    For as many of you as have been baptized into Christ have put on Christ.

Proof texts as given in the original; verse text from the King James Version.