The One referent in this passage is the Father our great God and Savior.
Supplementary information regarding Titus 2:13
THE
Blessed HOPE
AND
APPEARANCE of our great God and Savior’s glory
= Jesus
THE
Blessed HOPE
AND
APPEARANCE of [the Father’s] glory
= Jesus
The Son of Man will come in the glory of his Father. Matthew 16:27.
Age To Come 