Looking for our blessed hope, the manifestation of the glory of our great God and Savior, Jesus Christ.
Or (to avoid any trinitarian misunderstanding)
Looking for our blessed hope: the manifestation of Jesus Christ, the glory of our great God and Savior.
The great God and savior is the Father. In the same epistle and chapter, verse 1O describes God as savior:
Not purloining, but shewing all good fidelity; that they may adorn the doctrine of God our Saviour in all things.
Verse 11 confirms that God saves:
For the grace of God that bringeth salvation hath appeared to all men...
So why would Paul suddenly change his line of thinking and call Jesus Christ "great God and Savior" in verse 13 ? That is not plausible !
Jesus is the manifestation of the glory of God. Elsewhere (Col 1,27) Paul describes Jesus as the hope of glory. And in 2 Cor 4, 4 Paul speaks of the
"light of the gospel of the glory of Christ, who is the image of God".