The word of the Lord is compared to a seed which is sown in a field; those who hear it with faith and are numbered among the little flock of Christ have truly received the kingdom. Then, by its own power, the seed sprouts and grows until the harvest.
The kingdom belongs to the poor and lowly, which means those who have accepted it with humble hearts. Jesus is sent to “preach good news to the poor”; he declares them blessed, for “theirs is the kingdom of heaven.” To them – the “little ones” the Father is pleased to reveal what remains hidden from the wise and the learned. Jesus shares the life of the poor, from the cradle to the cross; he experiences hunger, thirst and privation. Jesus identifies himself with the poor of every kind and makes active love toward them the condition for entering his kingdom.
Jesus invites sinners to the table of the kingdom: “I came not to call the righteous, but sinners.” He invites them to that conversion without which one cannot enter the kingdom, but shows them in word and deed his Father’s boundless mercy for them and the vast “joy in heaven over one sinner who repents”. The supreme proof of his love will be the sacrifice of his own life “for the forgiveness of sins”.
Jesus’ invitation to enter his kingdom comes in the form of parables, a characteristic feature of his teaching. Through his parables he invites people to the feast of the kingdom, but he also asks for a radical choice: to gain the kingdom, one must give everything. Words are not enough, deeds are required. The parables are like mirrors for man: will he be hard soil or good earth for the word? What use has he made of the talents he has received? Jesus and the presence of the kingdom in this world are secretly at the heart of the parables. One must enter the kingdom, that is, become a disciple of Christ, in order to “know the secrets of the kingdom of heaven”. For those who stay “outside”, everything remains enigmatic.
From the Catechism of the Catholic Church 543-546