If One Has Faith in Buddhism, Does One Need to Become Vegetarian?

No. Although Buddhism encourages vegetarianism, it does not require all Buddhists to be vegetarians. Vegetarianism is a unique feature of Mahāyāna Buddhist practice, motivated by great compassion for all sentient beings. In countries where Theravāda Buddhism prevails a vegetarian diet is not required, even for the monks. In Tibet, lamas are not required to be vegetarians either, but they cannot personally kill living beings.

Since the first of the five precepts is not to kill, after becoming a Buddhist it is best if one can become vegetarian. But if for family or social reasons being a vegetarian is difficult, one can be excused for eating meat. In no case, however, is one permitted to directly kill or instruct others to kill. Buying the meat of previously slaughtered animals to bring home is permitted.

SOURCE:

Orthodox Chinese Buddhism: A Contemporary Chan Master's Answers to Common Questions. (2007)
by Master Sheng Yen | Translated by Douglas Gildow and Otto Chang. | ISBN 978-1-55643-657-4

ADDITIONAL NOTES ON SOURCE:

Lists of errata, suggested changes and comments by Douglas Gildow