Terrance Callan, «The Christology of the Second Letter of Peter», Vol. 82 (2001) 253-263

The Christology of 2 Peter is very exalted. The author calls Jesus God and speaks of his divine power. He uses the title ‘Lord’ both for Jesus and for God; in the latter cases there is usually some ambiguity about which of them is meant. However, the author presents God as a person distinct from Jesus, and there is no suggestion that the author would affirm the existence of two Gods. The transfiguration revealed Jesus as the son of God. It may be understood as an epiphany of the divine Jesus. It was a moment when Jesus received glory from God, in virtue of which he is praised like God.
        2 Peter reflects a stage in early Christian thinking when the word ‘god’ was used in two ways. Usually it was a proper noun that designated the one who revealed himself in the Hebrew scriptures. Occasionally it was used as a common noun that designated those who belonged to the category of the divine. In this way 2 Peter can call Jesus God without either identifying Jesus with God or seriously affirming the existence of two Gods. Eventually these uses were related in the doctrine of the Trinity.

        Using similar terms Tertullian explained the relationship between Jesus and the Father in a way eventually adopted by the whole church. In Apology 21 he says that the Word, who became flesh in Jesus, proceeded from God and was generated by God, and so is called the Son of God, but is called God because of unity of substance with God. The relationship of God and the Word is like that of the sun and a ray of light going forth from it, no division of substance, but merely an extension⁴⁷. Tertullian used this account of the relationship between Jesus and God to refute the charge that he believed in two Gods in Praxeas 13. See also Novatian, On the Trinity 30-31.

        There is no indication that the author of 2 Peter has anything like this in mind. He has probably not reflected systematically on the relationship between God and Jesus. He speaks of Jesus as God, yet regards Jesus as distinct from God and does not seem to think there is more than one God. When he speaks of the Lord, it might mean either God or Jesus, and sometimes it is not clear which. He stands near the beginning of early Christian use of ‘god’ in two senses. Most of the time he uses ‘god’ as a proper noun designating the one who revealed himself in the Hebrew Bible. But he can also call Jesus ‘god’ in a more general sense, meaning that he belongs to the category of the divine. However, he does not mean either that Jesus is the God who revealed himself in the Hebrew Bible, or that there is more than one God.