I swear by the god.

我对天发誓。

youdao

I swear by almighty God that I will tell the truth.

我向全能的上帝起誓，我以下所说句句属实。

《牛津词典》

I swear by Almighty God to tell the truth.

我向上帝发誓讲真话！

youdao

I swear by Almighty God to tell the truth.

我向上帝发誓讲真话！

youdao