'O God' in the Bible

We give thanks to God always for you all, making mention in our prayers;

for they proclaim concerning what kind of reception we had unto you; and how you turned to God from the idols, to serve the true and the living God,

And on account of this we also give thanks to God incessantly, because, receiving the word of God from us by hearing, you received it not as the word of men, but, as it truly is, the word of God, who indeed works in you who believe.

who even killed the Lord Jesus and the prophets, and persecuted us, and are displeasing to God, and hostile to all men;

For what thanks are we able to render unto God in your behalf, for all the joy with which we rejoice on account of you before our God;