'O God' in the Bible

Glory to God in the highest, and on earth peace, good pleasure in men.

And it came to pass in those days that he went out into the mountain to pray, and he spent the night in prayer to God.

There have not been found to return and give glory to God save this stranger.

And the tax-gatherer, standing afar off, would not lift up even his eyes to heaven, but smote upon his breast, saying, O God, have compassion on me, the sinner.

And immediately he saw, and followed him, glorifying God. And all the people when they saw it gave praise to God.

And he said to them, Pay therefore what is Caesar's to Caesar, and what is God's to God.