Jesus is not after behavior modification. Jesus wants heart and mind transformation. Jesus wants us to repent.
That is His challenge to us. Will we love God? Will we love everyone we meet every day? Will we have a heart after God?
Fortunate [Blessed] are the pure in heart, for they shall see God. 
Beyond our heart, Jesus challenges us to change our minds (repent).
Repent, for the kingdom of heaven is at hand.
The Greek for repent is μετανοέω mĕtanŏĕō — Meaning: I repent, change my thinking, change the inner man and change my behavior. Translation: radically change my thinking and behavior.
μετανοέω; μετάνοια, ας f: to change one’s way of life as the result of a complete change of thought and attitude with regard to sin and righteousness—‘to repent, to change one’s way, repentance.’
μετανοέω: ἐξελθόντες ἐκήρυξαν ἵνα μετανοῶσιν ‘they went out and preached that the people should repent’ Mk 6:12.
μετάνοια: ἀγνοῶν ὅτι τὸ χρηστὸν τοῦ θεοῦ εἰς μετάνοιάν σε ἄγει; ‘do you fail to understand that God is kind because he wants to lead you to repent?’ Ro 2:4.
Though in English a focal component of repent is the sorrow or contrition that a person experiences because of sin, the emphasis in μετανοέω and μετάνοια seems to be more specifically the total change, both in thought and behavior, with respect to how one should both think and act. Whether the focus is upon attitude or behavior varies somewhat in different contexts. Compare, for example, Lk 3:8, He 6:1, and Ac 26:20.
Source: Johannes P. Louw and Eugene Albert Nida, Greek-English Lexicon of the New Testament: Based on Semantic Domains (New York: United Bible Societies, 1996), 509.
What is the theology of Jesus? It is the kingdom [reign] of God. That is it. He starts his ministry there. He ends his ministry there.
The kingdom of God is synonymous with the kingdom of heaven. The concept of the kingdom of God takes on various shades of meaning in different passages of Scripture.
Broadly speaking, the kingdom of God is the rule of an eternal, sovereign God over all the universe. Several passages of Scripture show that God is the undeniable Monarch of all creation:
- “The MASTER has established his throne in heaven, and his kingdom rules over all” (Psalm 103:19).
- As King Nebuchadnezzar declared, “His kingdom is an eternal kingdom” (Daniel 4:3).
- Every authority that exists has been established by God (Romans 13:1). So, in one sense, the kingdom of God incorporates everything that is.
More narrowly, the kingdom of God is a spiritual rule over the hearts and lives of those who willingly submit to God’s authority.
- Those who defy God’s authority and refuse to submit to Him are not part of the kingdom of God.
- in contrast, those who acknowledge the Mastership of the Messiah and gladly surrender to God’s rule in their hearts are part of the kingdom of God.
- In this sense, the kingdom of God is spiritual—Jesus said His kingdom was not of this world, and He preached that repentance is necessary to be a part of the kingdom of God.
- That the kingdom of God can be equated with the sphere of salvation is evident in John 3:5–7, where Jesus says the kingdom of God must be entered into by being born again.
There is another sense in which the kingdom of God is used in Scripture: the literal rule of the Messiah on the earth during the millennium. Daniel said that “the God of heaven will set up a kingdom that will never be destroyed” (Daniel 2:44), and many of the other prophets predicted the same thing. Some theologians refer to the future, open manifestation of the kingdom of God as the “kingdom of glory” and the present, hidden manifestation of the kingdom of God as the “kingdom of grace.” But both manifestations are connected; the Messiah has set up His spiritual reign in the church on earth, and He will one day set up His physical reign in Jerusalem.
The kingdom of God has several aspects.
- The Master is the Sovereign of the universe, and so in that sense His kingdom is universal.
- At the same time, the kingdom of God involves repentance and the new birth, as God rules in the hearts of His children in this world in preparation for the next.
- The work begun on earth will find its consummation in heaven.
 The Holy Bible: English Standard Version. (2016). (Mt 5:8). Wheaton, IL: Crossway Bibles.
 The Holy Bible: English Standard Version. (2016). (Mt 3:2). Wheaton, IL: Crossway Bibles.