'O God' in the Bible

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

for they themselves concerning us do declare what entrance we had unto you, and how ye did turn unto God from the idols, to serve a living and true God,

Because of this also, we -- we do give thanks to God continually, that, having received the word of hearing from us of God, ye accepted, not the word of man, but as it is truly, the word of God, who also doth work in you who believe;

for what thanks are we able to recompense to God for you, for all the joy with which we do joy because of you in the presence of our God?

for if we believe that Jesus died and rose again, so also God those asleep through Jesus he will bring with him,