It’s interesting to me how Jesus used the same illustrations to bring out different points. This passage is an example.
Earlier, when he had sent his twelve disciples out, he talked about how everything concealed would be revealed, and how all that was hidden would be made known. There were many things that he had taught the disciples in private that the multitudes did not have access to. But he was telling them that this was not to be the case forever. Instead, he told them that what he had taught them in the darkness, they were to bring into the light. And that which he whispered in their ears, they were to proclaim from the rooftops. (Matthew 10:26-27)
Now Jesus uses these same pictures in a different context. He told his disciples,
Be on your guard against the yeast of the Pharisees, which is hypocrisy. (Luke 12:1)
He then told them that while they may hide what is in their hearts, it eventually would be revealed. The things that they said in the darkness, thinking that no one heard, would be heard in the daylight. And the secret things they had whispered would be shouted out from the rooftops.
In short, you can play being the good Christian, but if there is hypocrisy in your heart, if you are saying one thing, but living another, it will come out sooner or later, either on earth or in heaven.
So let us not simply play at being righteous. Let us be honest before God and others. Because if we aren’t, the truth will come out and we will be revealed for what we really are.