Sincerity of Heart
Here we have three separate passages that I have lumped together under the topic of sincerity of heart, or one might say, purity of heart. After all it is the pure in heart who will see God (Matthew 5:8). To be pure or sincere means to have no ulterior motives, to desire that for which you ask and nothing more, to love with the whole heart faithfully. This is hard for us because our hearts are so deceitful that we hardly understand them ourselves (Jeremiah 17:9), we want many things and not just one thing, and our loves are so mixed with self-interest.
First, Jesus convicts the Pharisees, who had just accused him of casting out demons by the prince of demons, for just such deceitfulness as described above. Jesus uses an illustration he used on other occasions about good trees producing good fruit and bad trees producing bad fruit. So it is no wonder that he expresses his amazement over the Pharisees! How is it that they can speak with mouths full of honey when their hearts are full of venom? Jesus then teaches us the truth that the tongue, as well as deeds, expresses our hearts. Then the fearful word comes: “I tell you, on the day of judgment people will give account for every careless word they speak, for by your words you will be justified, and by your words you will be condemned.” A timely word for our day!
So the Pharisees then ask Jesus for a sign, not because they want one (Good heavens! How many signs had Jesus already performed?), but to catch him in some violation of their law. Again, we see insincerity of heart. Jesus refuses to humor them but prophesies his own death and resurrection using the prophet Jonah as a sign, or a type, of what Jesus himself would soon do. That’s the sign he’ll give them, but naturally they won’t see it because they have not hearts that will see. Jesus then compares their generation with previous generations from the Old Testament in which even wicked people gladly heard a certain prophet, but these refuse to hear the Son of God!
The heart is such a tender thing that can turn this way or that. This is why we are told to guard it (Proverbs 4:23, KJV). Even after we think we have left some sin or demon behind, we can find ourselves recaptured in a time of weakness. Therefore, we must purify ourselves as he is pure, knowing that one day he shall appear and we shall see him as he is, for we shall be like him (1 John 3:2-3). God must become our desire, our passion, our all in all. Then we shall see Him, just as He promised.