It seems to me that there is a difference between "I think this is true" and "I am absolutely convinced that it's true." Most of us probably struggle with what to believe, for a very long time.
Being fairly new to primal/paleo, I am reading a lot. (I know I need to keep reading it, or I'll lose my conviction. ) But I do see that there are huge problems with the conventional information, and that concerns me a ton, even when I don't know what to think--I can't get past the fact that a lot of conventional science (both nutritional and other types) are really BAD science. When I see an article that's actually well done, I am surprised, which is a bad place to start, and this makes me far more likely to accept an alternative viewpoint.
However, all that said, one big thing is sticking out to me right now: would I rather be sick and tired and miserable all the time and live an extra year or two, or be healthy and happy for many years and eventually die perhaps a year earlier? Do I want to feel, all through my 50s, 60s, and 70s, the way I feel right now? Or do I want to be healthier and more energetic, even if I die at 84 instead of 86? I know some old people who have been unhealthy for many years, and I have to say, I'd rather be like my grandfather, if I can help it, who had sudden pain and then died within about 45 minutes, than like my grandmother who lived 5 years in a nursing home. I know that to some extent, even with a good diet, it cannot be helped, and a person who is very healthy might just live longer before they start a long decline. But I think that the health or lack of health I have in my 50s is going to influence the health or lack i have in my 80s, and the things that contribute to being healthy now will have a positive effect later, as well. And if they don't, well, honestly, a heart-attack at an old age is not the worst way I can think of to die.
So having thought it all through, I'm going to put my bets on health, now, and work towards what makes me feel energetic, healthy, and well, today.