Why salvation is attained through faith, not good deeds?

In Christian theology, salvation is attained through faith, not good deeds. There are a lot of explanations. All make me more confused. Then I realize the real explanation.

What your boss wants? He wants your obedience. He demands your faith to him. Your boss doesn’t necessarily want you to do good deeds. This might undermine his authority. 

Faith to your boss, or your god, is the only path to salvation, or good relation with your boss.