Acts 2:21
Acts 2:2121And everyone who calls on the name of the Lord will be saved.’
The Watchtower cites as a promise about "calling on Jehovah's name" — keeping worship exclusive to the Father. JWs read the verse as reinforcing that the Name belongs to Jehovah alone and salvation flows through calling on him, with Jesus as appointed agent rather than co-recipient.
Walk through Peter's sermon carefully. In verse 21 Peter quotes — a passage in which YHWH says "everyone who calls on my name will be saved." Peter then spends the next fifteen verses arguing from Psalm 16 and Psalm 110 that Jesus is the risen Lord, and concludes at : "God made him both Lord and Christ, this Jesus whom you crucified." The "calling on the name" promise of verse 21 lands on Jesus in verse 36. Paul makes the same move in — "if you declare that Jesus is Lord… everyone who calls on the name of Jehovah will be saved." The Joel worship formula is applied to Jesus in both sermons. Pair with — Christians are "those who call on the name of our Lord Jesus Christ." Same phrase, same exclusive worship posture, now directed to Christ.
Where the Greek at has κύριος (kyrios, "Lord") — Peter's citation of LXX — the NWT inserts "Jehovah." No extant Greek manuscript of Acts contains the Tetragrammaton; the insertion is editorial. The choice matters because Peter's sermon is argumentatively christological: verses 22-35 argue that Jesus is the risen Lord, and verse 36 concludes "God made him both Lord and Christ." Reading "Jehovah" at verse 21 and "Lord" at verse 36 obscures the christological arc Peter is building. Paul's parallel argument in runs the same way and takes the same NWT rendering at verse 13 ("calls on the name of Jehovah") while keeping "Lord" at verse 9 ("Jesus is Lord") — so the Joel promise is aimed at Jehovah in the NWT and the confession is aimed at Jesus, even though the Greek uses the identical word κύριος for both.