Wa Salaamun Alaik,
Indeed this significant topic of what does it mean to obey God and obey the messenger is a paradigm shifter - of equal magnitude to the notion that the earth is not the centre of the universe. Naturally, resistance will ensue in any conversation on this topic with those who orbit the status quo.
The "reasoning" behind those ayahs is vital and should have been taught to us when we were younger. Too often, those who espouse a Qur'an-centred universe (as opposed to a hadith-centred universe), cling to conclusions without completely considering and comprehending the underlying chain of reasoning and logic.
In other words, try not to simply seek out conclusions in the Qur'an, but also search for the premises/principles/ratio decidendi that the conclusion (ratio) firmly rests on. Interestingly, because the Qur'an uses Tasreef, many ayahs regarding a specific topic function as the premises, whereas others serve as the conclusions. In our zeal to repeal the false ideal of hadith we should not become guilty of just shooting out conclusions at our audience. But, maybe, a better strategy would be to construct the argument, brick by brick, verse by verse, premise by premise. Lead them through the chain of reasoning instead of bombarding them with conclusions, which from their perspective seems like a big pile of oxymorons.
Discussions about the Qur'an should obey some ground rules - reasoning and logic - those should be the unwritten rules of any discussion, especially about the Qur'an. Otherwise, it will be a he said she said, to-and-fro, fallacy-galore, stalemate. Albeit, such civil discussions need to occur more frequently between humans on such an important topic. The more people you converse with, the more you will hone your ability to advocate your position in the wisest and most persuasive manner possible.
Here's a useful article on the reasoning behind "obey God and obey the messenger."
[You'll have to please copy the whole link, not just click on the blue.]