Where should we be?

I am a student of English linguistics and literature. I have been encountering English since kindergarten. So basically I have a good English skill. Well, perhaps with some errors. Hey, I'm not a native speaker of English!
Yet, I know most of the grammatical rules and spelling conventions. But it always makes me crazy!

No, I'm not crazy because they're difficult. I can adapt to most of them. What makes me crazy is the people who don't know how to use them and end up creating based English sentences. Call me grammar Nazi but, yeah, I often correct people when they're speaking English.

I still can recall about right first lesson in linguistics about prescriptive and descriptive grammar. The lecturer said that linguists should be descriptive and see grammatical error or language failure as  unique phenomena and researchable stuffs. I have been trying to be descriptive but there urge to correct people's grammar is really strong in me!

Well by saying that I am correcting them to teach the'correct' form and make them learn the 'good' English, I am just making excuses. I don't want to offend people. Some people are happy when they are being corrected but to the other it might be taken as an offensive attitude.

God. Seems like I will never be able to satisfy all people.

But recently I have been trying to minimize my act of correcting people's grammar. I usually just sigh and pray, "God please save me from the horrible grammar mistakes and embarrassing mispronunciation, as Thou art The All-Knowing about everything including languages. Amen."

But seriously, I really have no idea whether I should let them do their mistakes (again and again) and be descriptive about these situation, or be prescriptive to share my knowledge about English grammar with them so they would not make the same mistake anymore.

But, yeah, in my brain I keep correct their mistake for myself. At least I can learn from other's mistake.

Let's pray together again.
"Our Lord, save us from the horrible granary mistakes and embarrassing mispronunciations, as Thou art The All-Knowing about everything including languages. Amen."