There is a whole host of evidence but quantitatively a lot of it is summarized in the following graph:
This shows a correlation between GDP and economic freedom. Granted, neither GDP nor economic freedom are perfect measures, and this graph alone does not prove causality and which direction it goes, but it does visibly summarize the effect of economic freedom (or the lack thereof) on national wealth. What it shows (in conjunction with all the available evidence) is that the more economically free a nation is, the wealthier it is. Or put negatively: the more it deviates from capitalism, the less wealthy it is. It is not in the near-capitalist societies that people are dying of malnutrition and disease. This happens in the poor, anti-capitalist countries. Thus, anyone who is promoting anti-capitalism is partially responsible for the deaths in anti-capitalist countries, because they contribute to the spreading of false, murderous ideas.
Now, you can of course now answer that this is bullshit, that this graph proves nothing, but consider what I am accusing you of: contributing to the deaths of thousands of innocent people every day. If *I* was accused of something like that I would have to pretty darn certain before dismissing it as bullshit. In fact, consider an analogous case: suppose there is a baby food producer, and several customers reported to you that there was something horribly wrong with the food that was making their children really sick. Suppose further that the baby food producer dismissed the complaints as bullshit and that their complaints prove nothing, and then proceeding to not do ANYTHING to test the food to see if there was anything wrong with it. What would your view of such a baby food producer be? I know that *I* would view him with contempt and hold him criminally responsible for deaths and illness caused by the baby food. Now, apply that same logic to yourself in the case of capitalism and see where that leaves you.