Jesus says, "I am the vine; you are the branches. Whoever abides in me and I in him, he it is that bears much fruit, for apart from me you can do nothing."
People who are connected to Christ through his word and sacraments can bear much fruit, that is do good works. Those who are disconnected from Christ can do nothing. Does that match up to your experience? We all know people who are not Christians who do good things. They love their families. They help their neighbors. They do their jobs diligently. Are not these things good works?
They are not.
Good works are only those things which are done from faith in God. When we are connected to Christ, his holiness flows through us into the good things we do, making them good actions before God in heaven.
Why is this important? You'll have to listen to find out more.