There is no line because there is no western culture, civilization, values, anything. It's a political term invented for superficial political goals. Just like the idea of 'the west'.
Ancient greek civilization based around the greek language, culture, religion, etc. Yes. What exactly is the language, culture, religion, etc of 'the west'. There is none.
If you think there is a 'west', then try defining 'the east'. It's an artificial designation that changes depending on one's political biases.
