Jesus sighed when the Pharisees came forward and began arguing with Him, seeking a sign from heaven to test Him. It was not a sigh of exasperation; it was a sigh "from the depth of His spirit. Often, I think, we get the perception that Jesus did not like the Pharisees. Perhaps there are many times when He doesn't like us; this is why He is constantly trying to change us. The Pharisees were men, part of the human race. God loves the human race. His heart goes out to us. For this reason, Jesus, the Son of God, true God, became incarnate, to give His life for us. He sighed from the depth of His spirit out of love for them.
Adam had sinned; now, he "knows" sin, "knows" evil. Then, he "knew" his wife, and what is the first-fruit of this "knowledge"? You will know the tree by the fruit it bears. The first-fruit is Cain, a murderer. This is what everyone is prior to Baptism. Although we may not commit the actual crime of murder, our Lord tells that we murder when we get angry at our brother.
Now, Cain was not rejected because of his sacrifice; his sacrifice was rejected because he, the man, was first rejected. "Not for your sacrifices do I rebuke you..." "Why do you recite my statutes, and profess my covenant with you mouth though you hate discipline and cast my words behind you? You sit, speaking against you brother, against you mother's son you spread rumors. When you do these things, shall I be deaf to it? Or do you think that I am like yourself? I will correct you by drawing them up before your eyes." The Pharisees' sacrifices were rejected because they were first rejected--although the sacrifices were in accordance with the Law. Although we are first born as Cain, through Baptism we are born of the second Adam and the second Eve and become as Abel.
Although God had rejected Cain and his offering, He still continued to reach out to Cain because Cain was His creation, was human; and, out of love, He reached out to him: "What have you done!" After Adam sinned, God reached out to him; now, He does the same to Adam's fruit. Cain does not accept his punishment; he accuses God of being too harsh. We do the same: We do not think we deserve some of the "bad" things that happen to us. These are all "signs from heaven." God chastises those He love; however, we must accept our punishment out of love, realizing that we deserve a much harsher punishment. If we do not believe we deserve what we receive, we are belligerent children. St. Irenaeus said that our life in this world is our punishment. Therefore, we need to accept all our circumstances with the right frame of mind, the right attitude, taking everything in stride.,knowing God is sanctifying us because of His love for us. We need His grace and mercy to do this.
Although Jesus said no sign would be given, He did give them, and us, a sign: He left them, got into the boat again, and went off to the other shore.We have to leave the world-view and pick up our crosses and follow Jesus. The boat is the Catholic Church. To the Pharisees, it would be the cross. The two go together. Because of the Cross, the Catholic Church aids us and keeps us safe. It will take us "to the other shore."
For this, God deserves praise, but how do we "offer to God a sacrifice of praise"? Through obedience and thanksgiving. Children honor and praise their parents through obedience and doing deeds that please them. In return, they receive blessings. If this is true with sinful humanity, how much more so with God, who is all-loving. As belligerent children, the Pharisees failed to see the love of God in Jesus. Today, we oftentimes, as belligerent children, fail to see the love of Jesus Christ, Son of God, in the Catholic Church. We rebel many times because we are not in agreement with its teachings, as if we are the authority. This is exactly what was occurring with the Pharisees. Nevertheless, God is still reaching out to us to repent--through the Catholic Church.
Why doesn't God give us a sign? Truthfully, He does; it is just not the one we are looking for, not the one we want to see. If He did give us a sign from heaven, we would rationalize it away.