whether I should create a new world or use the original world we live in?

[Aldarion]

I have a story in mind that I want to write, but I don't know whether I should create a complete new world to write it or should I use our current world structure (earth and continents, you know) to use in my story? The reason why I am asking this question is because in the story, I may to show some particular organisation as superior (some will say it as good, but since everybody has there own opinion of good and bad, I won't use that term) and other as inferior ? I don't want to offend any organisation while writing so that is why I am asking.
It may sound a silly question but I am asking it since this is my first time writing. Please tell me what should I do?

No matter what you write you will offend somebody, so not offending people is a fool's errand.

Just do whatever works better for your story.