Jehovah saves through Jesus. Jesus is the instrument of salvation, not the
source. Just as Jehovah used judges to 'save' Israel, he uses Jesus as
his agent of salvation.
This argument follows the same pattern as (sole Creator) and (won't share glory). Read in the NWT: 'besides me there is no saviour.' Then read : 'there is no salvation in anyone else.' Then read — even the NWT calls Jesus 'our great God and Saviour.' The logic is simple: if there is no saviour besides Jehovah, and Jesus is called saviour, then either Jesus is Jehovah or the Bible contradicts itself. Notice that does not say 'besides me, no one else can save on my behalf' — it says no saviour exists besides Jehovah. The title belongs exclusively to God.
Isaiah says no saviour except Jehovah. The NT calls Jesus saviour. Either Jesus is included in who Jehovah is, or the Bible contains a fatal contradiction.
Jehovah used human judges as 'saviours' in the OT — Jesus is like them.
The judges were called 'deliverers' (moshia) in a relative, temporary sense — they saved Israel from one enemy. uses an absolute statement: 'besides me there is NO saviour.' And Jesus doesn't save from one temporary enemy — he saves from sin and death eternally. says 'no other name under heaven' — not 'one of several names.' The scope of Jesus' salvation matches Jehovah's exclusive claim.
Titus 2:13 doesn't call Jesus God — it refers to God AND the saviour Jesus as two persons.
The Greek of uses one article for both — tou megalou theou kai sōtēros hēmōn Iēsou Christou. Granville Sharp's rule (Greek grammar) means both titles refer to one person: 'our great God AND Saviour, Jesus Christ.' Even the NWT Study Bible acknowledges this construction is debated. And uses the same construction: 'our God and Saviour Jesus Christ.'
Isaiah 43:11 means Jehovah is the ultimate source — salvation originates with him.
But 'besides me there is no saviour' is exclusive, not hierarchical. It does not say 'I am the ultimate saviour' — it says 'there is NONE besides me.' If Jesus is a separate being from Jehovah, then there IS a saviour besides Jehovah — and is wrong. The only way both texts are true is if Jesus is included in who Jehovah is.
Don't get into the Granville Sharp debate at the door. The core argument is the Isaiah 43:11 / Acts 4:12 pair — keep it simple.
Read until you can quote verse 11 from memory in the NWT wording, then read so you know Peter's whole speech, not only its last line. Look up and in the NWT yourself so you know exactly how they read. Practise the doorstep question aloud using only and ; leave Granville Sharp for later. Prepare for the reply that the judges were also called saviours, and rehearse the contrast between a temporary deliverer and the one name under heaven for salvation.