PERSON: We should install secular democracy in Iran for the benefit of the people!
ME: You do realize that the last time we got involved in Iran it was to crush secular democracy, right? [Insert long discussion about the history of modern imperialism, especially by US government]
PERSON: Wow! It really is all just a crock of shit! Fuck the government!
ME: That's what I've been saying!
Basically, in my experience, an overtly ideological approach is probably doomed to fail. People don't like to be evangelized to, especially politically. But if you don't present the ideology as much as point out the contradictions and lies of the ideology they're probably not aware they subscribe to, then you'll make much greater progress.
In my own life-experience, and in my experiences with other people, the process of changing a worldview is not a one-off thing. It's a protracted process of accumulating contradictions and flaws in their ideology/worldview... and at some point the person suddenly becomes aware that they no longer find their old worldview tenable.
And suddenly, whole new vistas of possibility open up with them.
Thing is, nowawadays, most people are so badly miseducated they lack the necessary historical and political context to understand even the most basic arguments. They think that the American Civil War was fought to end slavery and that we had no choice but to nuke Japan (for those of us in the United States). Make an argument to someone who has never gotten beyond that propaganda and you can get nowhere.
And of course the people who are committed to never seeing through the bullshit are unreachable, so a less overtly ideological approach based on historical and political education is generally much easier -- you will be able to sense pretty quickly if someone is open to questioning and if you should continue.