If he doesn't give a shit now, don't think it won't damage his confidence in the future.
I know that when you've tried everything, you resort to saying things for shock affect, done it myself, but it does not work.
When my 4 yr old just started blinking at me and carrying on regardless of MY behaviour I thought there must be something wrong with him... there isn't. We're simply very close and at present his confidence comes from knowing I love him really (much as a sibling will be horrible and forgiven instantly) but it certainly didn't make things better. There's no use thinking "well why is he respectful to his dad - and me when I'm with dad - and not me?" its a different dynamic.
What's helped was using (for me) the procedures that his pre-school have... much as I hated the fact, he was an ANGEL at pre-school.
We're still extremely close (you know the saying 'cut from the same cloth' well we are) but now because of (previously disliked) formal, repetitive procedures, we built respect as parent and child. We still get all the good bits of being so tight together, but there are firm boundaries that don't involved threats, shouting, unhappiness... its simple cause and affect.
Oh I still use the 'Santa won't visit' line... but these days, there's less need for it. Its bloody hard work, and it sometimes feels unfair (I'd rather have a debate yawn) but he gets three chances then its time out, no sticker, no treat, etc etc etc...
Harsh but fair but friendly. good luck!!