Why should the reference to Queen remain while references to God and country have been omitted? Bags' suggestion about being kind and helpful is, I feel, much more acceptable.
Zoe Williams' point about vague, aspirational statements (in the case of the oath - "being true to oneself"), is, I think, very interesting. There's no point young people being encouraged to have all sorts of lofty ambitions when, in reality, many of them will have next to no chance of achieving them. It's just kidding people that there is equality of opportunity when there is so obviously not.