So, what makes you a Buddhist? You may not have been born in a Buddhist country or to a Buddhist family, you may not wear robes or shave your head, you may eat meat and idolize Eminem and Paris Hilton. That doesn’t mean you cannot be a Buddhist. In order to be a Buddhist, you must accept that all compounded phenomena are impermanent, all emotions are pain, all things have no inherent existence, and enlightenment is beyond concepts.
It’s not necessary to be constantly and endlessly mindful of these four truths. But they must reside in your mind. You don’t walk around persistently remembering your own name, but when someone asks your name, you remember it instantly. There is no doubt. Anyone who accepts these four seals, even independently of Buddha’s teachings, even never having heard the name Shakyamuni Buddha, can be considered to be on the same path as he.
From What Makes You Not a Buddhist by Dzongsar Jamyang Khyentse, page 5