-- the universe won't wait for you
- The quality or state of being true: "the truth of her accusation".
- That which is true or in accordance with fact or reality: "tell me the truth".
- A person or thing regarded as perfect: "you're my ideal of a man".
- A standard of perfection; a principle to be aimed at: "tolerance and freedom, the liberal ideals".
So despite being Reshiram's hero, N's beliefs are ideals. All beliefs are ideals unless rooted in scientific fact. They may be made out to be truths in one person's mind but they are not in another's. Since N himself is currently questioning his so-called 'truths', therefore proving them to be malleable, truthfully, they are ideals. And he will continue to question and revise these ideals in his own mind as he travels with Satoshi-tachi.