black-and-white issue

a black-and-white issue (something that is very clear in meaning, there is no gray area in meaning — either you agree with it or you don't ) — нечто соверешенно бесспорное или очевидное; двух мнений быть не может; без вариантов (разг.); прописная истина

Example: It is wrong to murder a child. This is a black-and-white issue everybody agrees with. — Нельзя убивать ребенка. Это же совершенно бесспорно и очевидно.

[без вариантов]
[there's no two ways about it]

(it's) black and white (it's easy for someone to understand what's wrong and what's right) — это (же) очевидно; ...
≅ Это и к гадалке не ходи. (разг.)

Example: If we don't do anything to stop climate change, something really bad will happen. For me, it's black and white.(bbclearningenglish.com)