Ever since I started studying the Bible seriously I have noticed a curious fact: in the New Testament, it is very rare that Jesus is explicitly referred to as “God” (Greek theos). In fact, there are only two cases in the whole of the New Testament that Jesus is unquestionably called God (John 1:1; 20:28), although there are a small number of other passages in which the author is probably using the term God to refer to Jesus (John 1:18, Romans 9:5, Titus 2:13, Hebrews 1:8, 2 Peter 1:1), although each of these other instances are questioned in some quarters.
What is particularly interesting is that just a few years after the writing of the New Testament books we find other Christians who have no such hesitation. St. Ignatius of Antioch, who was a disciple of John the Apostle and died in the early 2nd century, shows no reserve is calling Jesus God: “For our God, Jesus the Christ, was conceived in the womb by Mary” (Ignatius Letter to the Ephesians 18:2); “love towards Jesus Christ our God” (Ignatius Letter to the Romans Preface); “I give glory to Jesus Christ the God who bestowed such wisdom upon you” (Ignatius Letter to the Smyrnaeans 1:1).
So why do the New Testament writers hesitate, or even refuse, to call Jesus God if they believed him to be divine?
Some, of course, would say that the N.T. authors did not, in fact, believe Jesus to be divine. But that ignores the overwhelming evidence of the N.T. writings. Even if Jesus were never called God in the N.T. it is still clear that the first Christians believed him to be divine. His authority to change the Law (Matthew 5) and to forgive sins (Matthew 9:1-3), as well as his exaltation as Lord of the Universe (Philippians 2:9-11, Colossians 1:15-20) are just a few examples showing that the N.T. authors believed him to be equal to God. So, again, why didn’t they just go around explicitly calling him God as later Christians would do?
The answer lies in the strictly monotheistic Jewish atmosphere in which the first Christians lived and breathed and the competing worldview of the ruling Roman Empire. To a first century Jew, there was only one God and that was the God of Israel. To apply the term God to another being would be to reject the strongest pillar of Judaism: monotheism. To the first century Roman pagan, on the other hand, there were many gods and applying the term theos to someone caused no more concern than calling him powerful or a ruler. So the first century Jewish Christians (and remember, all the first Christians were Jewish) had a dilemma: they understood and accepted that Jesus possessed divine attributes, yet they also held steadfast to Jewish monotheism, so how could they express this without being perceived as Roman polytheists? If they just blithely called Jesus God, most Jews (and pagans) would believe they were inventing yet another god in the pantheon of pagan gods – or they would have believed that the Christian equated Jesus with God the Father. In many ways, the revelation of the Trinity was the greatest linguistic challenge man ever faced.
So the New Testament authors closely guarded their use of the title God for Jesus, and used many other ways to express his divinity. No one reading the N.T. books in the first century would have questioned that their authors believed Jesus to be divine, but at the same time they would have also been clear that these authors did not believe Jesus to be the same person as God the Father. By being circumspect in their language, they were able to protect both their monotheistic beliefs as well as their conviction that Jesus was God.
Eventually, as Christianity grew it became more confident in its distinctive beliefs regarding the Godhead in contrast to both Judaism and paganism and so was able to more freely assign the title God to Jesus outright, as we see in the writing of St. Ignatius of Antioch. The belief didn’t change, but the language used to express it did develop.
For further reading: Jesus as God: The New Testament Use of Theos in Reference to Jesus by Murray J. Harris