I'm committed to abandoning bad ideas when they're exposed as such, in theory, at least. Surely, as a human, I do it imperfectly. But if you're talking to someone and there's nothing that can dissuade them, you're talking to that person about their religion. I'm not talking about my religion.
With that in mind, here's what it would take to convince me that Islam is particularly likely to bring about negative outcomes:
1) Show there's a good reason to believe there's a correlation between self-identified Muslims and negative outcomes. State clearly what your idea of a negative outcome is -- homicide rate, suicide rate, number of aggressive wars launched, legal rights of women, terrorist attacks. Use the largest sample sizes, please -- the worldwide population, going as far back historically as reliable data allows. Define your terms clearly and apply equally to the entire set of phenomena under analysis. No moving yardsticks.
2) Establish correlation between Islam and negative outcomes in such a way that it would make sense to say Islam plays a causal role. Explain where geopolitical, economic, and other factors fail to explain what you think Islam explains in terms of causation. For example, imperialism correlates consistently with poor economic outcomes for the imperialized, to the extent it makes sense to say imperialism generally brings about poor economic outcomes.
If you're among those who thinks Islam causes relatively terrible things to happen, what would it take to convince you otherwise?