religious troubles

I was raised and educated as a Catholic but have been totally non-religious since the age of 18. Now I'm raising a child and I face a kind of conundrum in explaining to him (he's just six) what religion is - and what race is.

Olle's best friend Joe comes from a family of practising 'cultural' Jews - and his mother is half Chinese. Joe is very brown.

The other day over dinner Olle asked 'Are we Christians?" 'No' 'Are we Jews?' 'No.'
'So we're Aussies'.

We explained that everyone who was born in Australia (I leave out the small matter of the recent court judgment that a girl born here is not entitled to Australian citizenship...) is Australian (I can't bring myself to use that word, 'Aussie'). He interjected to say that one girl from a Chinese family is not Australian. Why he chose her, when there are several Asian kids in his class, I don't understand. We assured him that she is Australian and explained that co-parent, who was not born here, had become Australian by going through a ceremony.
So everyone in his class is Australian, but some are also Jewish... I begin to name the Jewish kids: "Joe, Hannah..."

"Hannah is not Jewish, she isn't the same colour as Joe".

I insist that Hannah is Jewish and add the names of other friends of ours, reminding him of the Passover feast we went to this year.

At the library the next day I looked for simple books on religion for a six year old. Most of them were oriented more towards older kids, but I did get one called "Sam's Passover" and another on respecting cultural differences.

Yesterday, applying sunscreen, he said something about Joe being brown. I said that Joe looks more like his Chinese grandmother than his (blonde) Jewish relatives. Olle chanted "Joe is Chin-ee-ese". (And in the way of most conversations with children, which are highly fragmentary, something happened to change the subject, so I didn't get the chance to address this.)

I was speaking to a Jewish friend of mine about all this on the phone last night. She suggested depicting Jewishness and Christianity and our own non-religious household as a matter of different families having different stories that they share and enjoy. But our lack of religion also feels like a lack of tradition - and it's hard to convey a lack in a positive way...

This morning, walking to school, I decided to talk to him about not 'making fun' of other kids - I was worried that he might make a declaration about Joe's Chinese background, either to Joe or to a larger audience. I said, among other things, you wouldn't like it, would you, if someone said to you [in a singsong voice] 'Your grandad's dead'.

Immediately his face crumpled and he began to sob. We went into the schoolground, where Joe repeatedly asked me why Olle was crying. Olle kept crying, wiping snot onto his shirt and managed to tell me it was because "you teased me". I apologised and told him I was only giving him an example and that no one likes to be teased, whether it's for having curly hair or red hair or straight hair...

I really screwed that one up, leaving my lovely boy in tatters at the start of the day.

Any suggestions welcome.