It's best to be honest from the beginning. Giving a false explanation now that you'll have to correct later is just more work.

Well... To be fair Santa is also regional. Klaus is the one who punishes bad kids and brings them to hell so that's true. One version of Santa is a drunkard who in probition became cheery, rosy cheeked, and so on during probition going from leaving out alcohol to milk and cookies. Chris Kringle and the bringing children who'd been chopped up back to life and together in a barrel.
Jeez. Santa has the same stuff as gods. Except we can trace many origins of Santa with some aggreement. The green man is one of my favourite Santa which is transitionary.

I would just say when you get old and die santa comes and turns your lifeless corps into toys for little boys and girls.

You can’t fool me. There ain’t no Sanity Clause! - Chico Marx

Honesty. It's critical.

Be honest from the beginning, if they want to become religious that's their choice. I don't agree with indoctrinating kids at an early age when they are so malleable, to me it's like forcing them to believe as they have no choice.

There are times that lying to your children is in their best interests. I don't see how lying to them about God or Santa Claus is helpful to their emotinal or mental development.

God vs Santa? All I know is Tokyo will be the big loser.

Maybe? If they're taught as stories, just like our modern day fairy tales, they can be beneficial in helping children understand why being human is so complicated. The stories of God and his own kids and the infighting among the angels, these are how families struggle, and learning to work it out WITHOUT Armageddon is a powerful lesson.

When a child reaches the age where it's time to tell him/her the truth about Santa, that's when they should be told the truth about God, as well.

I talk to my 11 year old honestly, she knows I'm an atheist but was brought up a Catholic so I can give her both sides of the argument. I just tell her to question everything and develope her critical thinking. If she's taught how to think she'll be ok and come to the same conclusion as me. I won't impose atheism on her or that would make me no better than those I oppose.

Same meat different gravy.

No only nothing of value, you have lied to your child, and that lie may have adverse consequences

Death is a tricky one but kids are smart. In my own life I think being active in remembering the person - retelling stories with others who loved the person - is my way to deal with grief. God need never be a factor when you smile (I hope) and remember the person as they were. Santa/Easter Bunny/Tooth Fairy for my kids is a story - lol!