The parables in Matthew 13 are concerning the mysteries of the kingdom. This does not mean that these mysteries are not reality. In fact, these mysteries are themselves the reality. The difference is that this reality was presented by the Lord Jesus to His disciples in a mysterious way and not in an open way. He presented the mysteries of the kingdom in such a way that only those who have a heart after God's desire can understand them. Those who are indifferent toward God's interests will find the parables very difficult to understand.
In Matthew 13:11-15 the Lord Jesus told the disciples why He used parables as the means to reveal the mysteries of the kingdom. He spoke in parables because the religious leaders, although apparently very religious and for God, were actually indifferent toward God's interests. They had the forms and the appearance of seeking God, but not the reality. They were not sincerely concerned about God's desire.
Previous to this time, in Matthew 12:46-50, the mother and brothers of the Lord Jesus came to see Him, wanting to speak with Him. When the Lord Jesus learned of this, He asked, "Who is My mother, and who are My brothers?" He considered His brothers and sisters, not according to their flesh, but according to their concern for the will of God. Whoever is concerned for the will of God is His brother and sister and mother. This indicates that by the time of Matthew 12, the Lord Jesus had given up the Jewish people. According to the flesh, the Jews are the Lord's brothers. However, at the end of Matthew 12, the Lord Jesus gave up that relationship. No longer did He have a relationship with anyone according to the flesh. Henceforth, His relationships would be in the Spirit and related to the will of God. Because the Jewish people cared only for the forms and appearance, with no care for God's concern, the Lord Jesus gave them up. After this, He began to speak about the reality of the kingdom in parables, not in an open way, but in a mysterious way.
Throughout the past centuries of Christian history, these parables have not been fully understood. During the first year after I was saved, I began to read the book of Matthew. As a young Christian, I was very ambitious to know the Bible thoroughly. So I decided to write down every verse I did not understand, and eventually, I had too many verses. Because of this, I purchased some books, especially on Matthew 13. Some taught that we are the ones who purchased the field (13:44). They gave a reference of Philippians 3:7-8, indicating we must sell everything in order to buy the field.
Other books indicated that the great tree was something positive (Matt. 13:32). These books said that, at the beginning, Christianity was like a little seed sown by the Lord Jesus, but now, in its greatness, it has become something marvelous and magnificent. This kind of interpretation indicates that their eyes were blinded. In this very chapter the Lord Jesus gave us the interpretation of the birds, telling us that they were Satan and his evil angels (Matt. 13:19). These evil spirits, the birds, lodge in the great tree. It is the birds of the air, not the Triune God nor the saints, that lodge in the branches of the great tree. This proves that the great tree is connected to Satan. How, then, can we regard the great tree in a positive sense? The church is the dwelling place of God, where God makes His home. The great tree, however, is different. The church can be compared to the vine tree of John 15, but not to that great tree of Matthew 13. The vine tree is not useful for producing material goods. Have you ever seen furniture or a house built out of a vine tree? The vine tree is good for producing grapes and wine—something to eat and drink. Likewise, the church must be small, not a great structure, but full of something to eat and drink. The fact that the evil birds lodge in the branches of the great tree proves that this tree is something negative.