"Do people pick grapes from thorn bushes, or figs from thistles? Likewise every good tree bears good fruit, but a bad tree bears bad fruit. A good tree cannot bear bad fruit, and a bad tree cannot bear good fruit. (Matt 7:16-18)
"Either make the tree good and its fruit good, or make the tree bad and its fruit bad. You brood of vipers, how can you, being evil, speak what is good? The good man brings out of his good treasure what is good; and the evil man brings out of his evil treasure what is evil. " (Matt 12:33- 35)
Does Jesus tell us these stories in order that we may learn more about plant life? Was He here to teach us about botany? If not, what is Jesus saying here in these stories? Jesus is not teaching us about botany, but is speaking rather plainly about us, about the human condition after the fall.
Thorn bushes, he says, do not produce grapes and thistles do not produce figs. Due to a plant's DNA such an outcome is an impossible supposition. He is communicating for our benefit, via parable, that persons ONLY produce fruit in accord with their nature. He was not teaching us botany lessons here. What you are, he explains, determines what you think and what you do. It cannot be otherwise. By nature we are all like thorn bushes. Apart from the supernatural work of the Spirit to change us, our heart is like fallow ground. Only as God plows up the fallow ground do we have hearts which can receive the seed of the gospel. The church casts the seed but only God causes the growth.
In the Old Testament, God made it clear to the Israelites that their obedience to His will was crucial for their physical and spiritual well-being. One of the ways that He did this was by warning them that if they did not obey Him, their crops would fail, despite their labor and efforts to sow seed. This demonstrates that while human effort and hard work are important, they alone cannot produce fruitful results without God's prior blessing.
In the New Testament, Paul uses an agricultural metaphor to explain the nature of evangelism. He compares the planting of the gospel to sowing a seed and emphasizes that while different individuals may be involved in the process of evangelism (e.g. planting and watering the seed), it is God who ultimately gives the growth. This means that evangelism, like farming, is not simply a matter of human effort, but is dependent on God's blessing and sovereign will. Therefore, we must rely on God's power and grace, rather than our own abilities, in order to see true and lasting fruit in our evangelistic efforts.
Note that Jesus says "make the tree good and its fruit will be good". Well, we all know that a tree cannot make itself good or bad. Only God has the ability to make a tree one way or another. So only a totally new tree will do. Likewise, being corrupt by nature, only God can make the heart good that we might see his goodness, believe and produce good fruit. The new birth is not simply helping us to become better people but making us totally new people. Those who, therefore, believe in libertarian free will must explain away these passages which actually have a very straightforward meaning.
If persons ONLY produce fruit in accord with their own nature, the question is, can we change our natures by our own will or effort or desire? Romans 9:16 says we cannot: "It does not depend on man's desire or effort but on God's mercy." If we hate God by nature as the Scripture attests (John 3:19, 20), does a change of heart come about naturally? The Scripture answers this when it says,
"Can the Ethiopian change his skin Or the leopard his spots? Then you also can do good who are accustomed to doing evil." (Jeremiah 13:23)
In other words, if a leopard can will his own spots away, then you have the moral ability to do good. The ability to turn in repentance and faith in Christ is about as likely as the ability of an Ethiopian to change his skin. To put it simply, impossible. But "what is impossible with man is possible with God" (Luke 18:27), Jesus said.
In John chapter 10, Jesus speaks to the same issue again. Some, He says, have been set apart as his sheep. The sheep recognize the voice of their own shepherd. But some do not believe BECAUSE they are not His sheep.
"But you do not believe because you are not of My sheep. My sheep hear My voice, and know them, and they follow Me." (John 10:26-27)
Who they are determines how they will respond. When speaking to some unbelieving Jews, Jesus makes the same point:
"Jesus replied, "I tell you the truth, everyone who sins is a slave to sin..."If you were Abraham's children," said Jesus, "then you would do the things Abraham did. As it is, you are determined to kill me, a man who has told you the truth that I heard from God. Abraham did not do such things. You are doing the things your own father does...You belong to your father, the devil, and you want to carry out your father's desire. He was a murderer from the beginning, not holding to the truth, for there is no truth in him. When he lies, he speaks his native language, for he is a liar and the father of lies. Yet because I tell the truth, you do not believe me! Can any of you prove me guilty of sin? If I am telling the truth, why don't you believe me? He who belongs to God hears what God says. The reason you do not hear is that you do not belong to God." (John 8:34-47)
Jesus calls these Jews sons of the Devil. As offspring, that is just who they are by nature, and so they cannot and will not hear Christ's words. Jesus says, only those who belong to God hear what God says. In other words, hearing God's voice requires the prior blessing of the Spirit to change the heart and unplug one's ears that they might hear the gospel and believe. For hearing and embracing the gospel without the Spirit is about as likely as a man totally deaf from birth listening on headphones to Bach. Likewise, shining a bright light into a blind man's eyes, do not help him to see. He needs new eyes to see... and that is our condition apart from the new birth.
Martin Luther once said that commands of God that contain statements such as ..."if thou art willing", "if thou hear", "if thou do", declare, not man's ability, but his duty. The commandments are not given inappropriately or pointlessly; but in order that through them the proud, blind man may learn the plague of his impotence, should he try to do as he is commanded."
We are never so close to grace as when we understand and despair of all hope from ourselves.