Why eat of the food which is already offered to dieties? You
cheapskate izzit?
Offering food to dieties or the dead but it's the living who eat
it later?
Well, you are teasing the dieties and the dead. What kind of
respect is that?
Better to give the dead the proper respect while they are still
alive. Let them actually eat to their hearts'content before they
meet their maker.
Really? Your dead ancestors will go hungry if you don't offer
them food?
Put a wig on you!
This is the belief of other people, so for that very
reason alone you should respect it.
The reasons to you should not matter in itself, even if you do
not believe it yourself. What matters is respect the belief of
others, and you respect the right of others not to believe.