May God bless you with eternal happiness.

Mr. TomIs this a natural expression

No. I would never utter such a phrase. It is limited to ardent preachers and ultra-religious greeting cards.

It is unnatural because the word eternal can imply the supernatural, or time after death. The sentence is grammatically correct, but I certainly wouldn't buy a card with it.

I agree that it is correctly structured, but it's definitely not something you hear or read every day. The inclusion of the word "eternal" makes me question if the person being addressed is still alive.

Thanks, MM, Philip and Ozzourti.

I want to use a natural expression in which I can use the word happy/happiness. Do any of these work?

May *** give you happiness.
May *** bestow happiness on you.
May *** make you happy.
I wish you a lot of happiness.
May Go bless you with happiness.

Tom

Those are all fine.

You just forgot the "d" in the last one.