De is the second most common word in the Greek New Testament (after kai), appearing about 2,792 times. It is a postpositive particle — meaning it cannot stand first in a sentence — and it signals a mild contrast ("but"), a continuation ("and, now"), or a transition ("then").
Where kai adds and connects, de distinguishes and advances. It can mark a gentle adversative ("but on the other hand"), a narrative transition ("now"), or a logical development. Context governs which nuance is present.
The famous "divine but" — de used as adversative — appears in some of the most powerful verses of grace in the NT. "But (de) God demonstrates his own love for us in this: while we were still sinners, Christ died for us" (Romans 5:8). The de pivots from human sin to divine action.
Ephesians 2:4 — "But (de) God, who is rich in mercy…" — is perhaps the single most grace-packed de in Scripture. The entire movement of Ephesians 2:1–10 is structured by this pivot: our deadness → God's life-giving action.
In Gethsemane, Jesus uses de: "not what I will, but (alla, stronger) what you will" — here the variant alla is used for a stronger contrast. But throughout the NT, de marks the turn from problem to solution, from law to grace, from sin to salvation.