Desiring a reward
There is no one thing that is whole or perfect on its own, and the truth is a combination of lots of things.
For example, let's ask ourselves: is it a good thing that some religious people expect to be rewarded with heaven? What I mean is: is it a good thing that some religious people do the good things that they do only because they **desire** to go to heaven?
If they desired heaven, then it would become a duty on them to do as the book says, whether they believed in it or not. So since their purpose is heaven, the book becomes the means towards that purpose, and then they would have to do what it says whether they truly believed in it or not. The most important thing would be in that case that they should follow its rules.
So even though they claim to be 'spiritual' but in fact this kind of thinking is as materialistic as doing business. I'll do what you say, and you'll reward me.
We have to love the truth, for the sake of the truth itself. And if we did good, we have to do good for the sake of good itself, and because we love good; not because we desire some kind of a reward. And we should not expect anything in return. So we have to love the truth even if we *knew* that there is no heaven. And if there was, it would be a heaven of equality, and all of us would be equal in it.