Everything is subjective. You write from your own unique perspective and even if you try to present an objective argument you find that true objectivity is like the fruit dangling above Tantalus in Greek mythology (whenever he reached for the fruit it moved just out of reach). We would like to believe that our most revered reference works give a balanced and objective view of the world but even the most academic entry in an encyclopedia has been written from someone's point of view (and reviewed by other learned people often with very similar viewpoints and frames of reference).
This is why Wikipedia is so fascinating. On its 10th birthday it's in the media focus and there are plenty of articles and blog posts on this theme just now. The idea of a collaborative encyclopedia that everyone can edit is inspiring but there are huge problems. Whose "truth" is most valid on Wikipedia? That's the topic of a fascinating article on Slate called Jesus of Wikipedia . The wikipedia entry for Jesus Christ is one of the encyclopedia's most troublesome since just about everything written about him has been contested by somebody. As soon as one version was published new edits were made. Sometimes finer theological issues were disputed, sometimes the whole question if his existence was challenged and sometimes there were simple acts of digital vandalism.
In the end the entry has been "locked" and only a few trusted experts can now edit. This keeps the digital vandals at bay for a while but somehow defeats the original vision of Wikipedia as an encyclopedia that everyone can edit. Similar problems have afflicted other religious figures in Wikipedia as well as controversial political movements. The discussion tab on a Wikipedia page presents a history of the changes made to the entry and an insight into the problems of presenting a "balanced" view of any topic. If you want to get a flavour of the controversial issues the discussion tab is the place to go.
Somewhere along the line, however, you have to decide whose truth is most valid or at least present the most important interpretations. Letting everyone edit freely is probably just not practical.
For a general summary of the state of Wikipedia on its 10th birthday, here's the official video.