The use of "so"

[Rachel Adams]

Could you please explain the use of "so" in this context? It starts at 0:57.
I was trying to turn on subtitles, but it says they are not available for this video.

https://youtu.be/NvKzPZl3Bds

 

[jutfrank]

I gave you life and I will instruct you on what you do with it, or so help me, I will take away the life God gave you.

On the surface, he's invoking God to give him strength to carry out his threat, should it be necessary. The bolded expression shows that he's serious about what he says.

 

[Rachel Adams]

I gave you life and I will instruct you on what you do with it, or so help me, I will take away the life God gave you.

On the surface, he's invoking God to give him strength to carry out his threat, should it be necessary. The bolded expression shows that he's serious about what he says.

Is it a fixed expression?

 

[jutfrank]

Is it a fixed expression?

Yes.

https://idioms.thefreedictionary.com/so+help+me
https://dictionary.cambridge.org/dictionary/english/so-help-me

 

[emsr2d2]

Is it a fixed expression?

Yes. You'll hear "so help me/you/us/them". You'll also hear "God help me/you/us/them" with the same meaning, although the latter has another meaning too.

 

[probus]

In my region you'll often hear them both combined for extra emphasis: "So help me God."

 

[emsr2d2]

In my region you'll often hear them both combined for extra emphasis: "So help me God."

That's also the case where I live.