[nanijoe]

The majority of the opening part of a Chess game is spent trying to force your opponent into a variation of an opening that you are most comfortable with. To be a good Chess player, you would need to be at least aware of most of the main lines, and then really master a few.

[TylerE]

Hardly. I know quite a few 2000-2200 rated players that don't know many openings...but are very strong tactically and at endgames.

[Codhisattva]

Much depends on the level of play you are at. Beginners flounder through weak openings while intermediate players know the main lines of the popular and strong ones.

There's really not a "master" for openings. After the first dozen moves or so you'll have your first exchange and the beginning of the middle game.