4 Therefore we were buried with Him through baptism into death, that just as Christ was raised from the dead by the glory of the Father, even so we also should walk in newness of life.
death, here, is Christ’s death, not ours
glory = excellence of God’s power manifested in the resurrection of Christ
newness = new in quality
When Christ died, we died. When He was buried, we were buried. When He was resurrected, we were resurrected. By faith we are united with Him. We are also glorified with Him — Ephesians 2:5-6 — Even when we were dead in trespasses, made us alive together with Christ (by grace you have been saved), and raised us up together, and made us sit together in the heavenly places in Christ Jesus.
Paul is still answering the question from Romans 6:1.
This verse doesn’t refer to our future resurrection (although that is assured) but to our present resurrected life in Christ.
We are accepted that we may be possessed, and possessed after the manner not of a mechanical “article,” but of an organic limb. We have received the reconciliation that we may now walk, not away from God, as if released from a prison, but with God, as His children in His Son. Because we are justified, we are to be holy, separated from sin, separated to God; not as a mere indication that our faith is real and that therefore we are legally safe, but because we were justified for this very purpose, that we might be holy. The grapes upon a vine are not merely a living token that the tree is a vine, and is alive; they are the product for which the vine exists. It is a thing not to be thought of that the sinner should accept justification — and live to himself. It is a moral contradiction of the very deepest kind, and cannot be entertained without betraying an initial error in the man’s whole spiritual creed. (quote from Bishop Moule in Barnhouse, pg. 61).
The ground of our justification lies in the fact that the Savior took not only our sins, but our sin upon the cross. God never deals with sins until He has dealt with sin. Barnhouse, page 61