What defines a person?
A person is what he thinks? Not necessarily, a lot of people think things they don’t apply in real life. Plus you don’t always know what they really think.
A person is what he believes? Even more than the previous point, a lot of people don’t really live by what they believe.
A person is his religion? Nobody follows their religion with 100% accuracy, and even if they think they do, they more or less follow their own understanding of it, which makes it pretty undefinable.
A person is what he says? Ever heard of lying, diplomacy, plain old hypocrisy…etc? All that tells us we can’t use what a person says to accurately define them.
A person is what he does? I know a lot of people will disagree with me, but I personally think this is the closest to the truth of what a person really is: what he actually does.
Of course, nobody should judge people solely on what they do, everything has to be taken into consideration, and context is very important always, but in the end: what a person does, given what you know about him (thinking, beliefs, religion, what they say about theirself) is what really defines that person.
So if we look at it using numbers, I’d say what a person does accounts for 60-70% of what they are, with the other elements taking up 30-40%