Opposite of buddhism Is there anything considered the opposite of Buddhism? I have guesses and I'm thinking contrasts might give interesting insights. 

In my limited understanding, the concept of an "opposite" to Buddhism is over dichotomising. I think some meaning might be put to it though if we consider what's offered as "not-buddhism" here The Four Seals of Dharma and consider thoughts, actions, and other deeds which might increase suffering for oneself and others. 

What are we likely to believe that runs contrary to Buddhism and is likely to cause harm?

Possible examples below. 

For each of Rinpoche's points we have:

"All compounded things are impermanent": A negation would be "Some compounded things are permanent." While the opposite would be "All compounded things are permanent." We readily see the opposite is false just by virtue of things being able to move. What things can we consider permanent? If we just postulate the existence of such, what are implications and what destructive actions might they lead to? I draw a blank here. 

"All emotions are painful": Any contrary to this whether a negation or a precise opposite would probably imply some clinging. If we regard an emotional state as truly representing reality, we are likely to cut ourselves off from reality. Does any emotional state entail a bit of ego, a certain false self distorting our perspective? We also have the dualism problem Rinpoche elaborates. 

"Everything is empty; lacking inherent existence": He simplifies, The way things appear is not the way they actually are. The opposite would be, appearances are never deceiving. This means we should never doubt our first impressions.Now impressions are often out of context. What we think they are, we think they are, despite other impressions giving us more insight. I think this would increase delusion.

"Nirvana is Beyond Extremes": I'm not sure what this means in its original form and have no guesses as to what might constitute an opposite.
Well, first point... Things do not have opposites. Things simply are. Qualities have opposites, and to the extent that a 'thing' is seen as an epitome of certain qualities, we can point at other 'things' that have opposing qualities. So (properly speaking) Buddhism doesn't have an opposite, although there may be other movements that try to create exactly the opposite of the qualities that Buddhism strives for.

With that in mind, I'd point at any kind of fanaticism: political nationalism, religious fundamentalism, commercial exploitation, ideological extremism... any movement that intentionally distorts perception and understanding, and purposely creates turmoil, in order to advance some abstraction. I'll leave examples to the reader, so as not to politicize.