This is a matter of capital importance.
I look forward to hearing your thoughts on this matter.
This is considered to be a matter of great importance.
No matter how often I tell her, she keeps making the same mistake.
It doesn't matter.
What's the matter?
It is not what you read but how you read that matters.
Let's discuss the matter right now.
No matter how important the question may or may not be, you must solve it.
Whether you like it or not doesn't matter.