Wouldn't denial of AGW equate to one of the following beliefs?

1. Climate sensitivity to doubled CO2 is zero, less than zero, or so poorly defined that it could straddle either side of zero, depending on the precise definition.
2. Increased levels of CO2 have nothing to do with human activity.

Anyone who believes in ~1 and ~2 must believe in some degree of AGW, even if they further believe it is trivial, or masked by natural climate variations.

Belief that sensitivity is below 2 degrees doesn't seem utterly unreasonable, given that the typical IPCC estimate is 3 degrees +/- 1 degree, the confidence interval is not more than 2 sigma either way ("likely" rather than "very likely" in IPCC parlance) and building that confidence interval involves conditioning on lots of different sorts of evidence. Belief that sensitivity is below 1 degree does seem like having an axe to grind.

All this is Charney or "fast feedback" sensitivity. The biggest concern is the growing evidence that ultimate (slow feedback) sensitivity is much bigger than Charney (at least 30% bigger, and plausibly 100% bigger). Also, that there are carbon cycle and other GHG feedbacks (like methane), so the long-run impact of AGW includes much more than our own CO2 emissions. Multiplying all the new factors together tuns a central estimate of 3 degrees into a central estimate of more than 6 degrees, and then things really do look very worrying indeed (temperatures during the last ice age were only 5-6 degrees less than today; at temperatures 6 degrees more than today there have been no polar ice caps at all).