By Stephen W. Hiemstra
God is holy; we are not. Our tension with God often starts with guilt over this holiness gap. This gap, which is more of a chasm, points to our need for Christ because we cannot bridge it on our own . The existence of this gap is explains why the gift of the Holy Spirit is foundational for our faith and for the establishment of the church. But first, let’s talk a bit more about the gap.
What does it mean to be pure in heart? The Greek word for pure, καθαρός, means “to being free from moral guilt, pure, free from sin” (BDAG 3814 (3c)). The Greek expression, pure in heart (καθαρὸς τῇ καρδίᾳ), is only here in the New Testament but arises in the Old Testament—
“Who shall ascend the hill of the LORD? And who shall stand in his holy place? He who has clean hands and a pure heart, who does not lift up his soul to what is false and does not swear deceitfully.” (Psalm 24:3-4 ESV)
—in the context of worship in the temple in Jerusalem. In view here is the holiness code of Leviticus where God admonishes us many times: “be holy, for I am holy” (Lev 11:44).
The emphasis on the heart in English translation is somewhat misleading because the response expected is not limited to emotions, which the English infers. The Hebrew expression for heart, לֵבָב, means “inner man, mind, will, heart” (BDB 4761). This is not wordsmithing trivia. Immediately following the Shema  we are commanded—”You shall love the LORD your God with all your heart and with all your soul and with all your might.” (Deut 6:5 ESV)—which emphasizes this point (heart, soul, might) through repetition . Jesus reminds us of this verse in Matthew 22:37 where he gives us the double-love command (love God; love neighbor; Matt 22:36-40)
The promise of seeing God, if we remain pure, is a promise of forgiveness (Ps. 51:10-11) and salvation (Job 19:27), but it is also a call to ministry. Seeing God figure prominently in the call stories of both Moses (Exod 3:6) and the Prophet Isaiah (Isa 6:5). Similarly, Paul is blinded by light in his call story which parallels the call account of the Prophet Ezekiel (Ezek 1:28) . Seeing God blinds us and threatens our very existence, as unholy beings.
The promise of seeing God is also a promise of restoration of the relationship with God, as we first saw in the Garden of Eden (Gen 3:8-9), which is also a picture of heaven. For example, in the last chapter of the Book of Revelation, we read:
“No longer will there be anything accursed, but the throne of God and of the Lamb will be in it, and his servants will worship him. They will see his face, and his name will be on their foreheads.” (Rev. 22:3-4 ESV)
In some sense, holiness is the mark of God on our souls, as well as our foreheads. This surprising idea is not a new idea; it is an old one. In Genesis we read:
“Now Abimelech had not approached her. So he said, Lord, will you kill an innocent people? Did he not himself say to me, She is my sister’? And she herself said, He is my brother. In the integrity of my heart and the innocence of my hands I have done this. Then God said to him in the dream, Yes, I know that you have done this in the integrity of your heart, and it was I who kept you from sinning against me. Therefore I did not let you touch her.” (Gen. 20:4-6 ESV).
What is most surprising here is that Abimelech is a gentile, not a Jew. Yet, God works in his heart to keep him from sinning and speaks to him directly.
It is indeed ironic in this beatitude to see Jesus, a “friend of … sinners” , placing a high value on and teaching about holiness knowing what was to come. John’s Gospel ends with Jesus offering the Apostles a commission—”As the Father has sent me, even so I am sending you” (John 20:21 ESV)—and anointing them with the Holy Spirit—”Receive the Holy Spirit” (John 20:22 ESV). Clearly, purity of heart was a prerequisit for ministry and the Holy Spirit brought purity of heart within their reach. Still, the Apostles had to appreciate and desire the gift.
 The exclusiveness of Christ arises, in part, because he is both God and man which is a necessity for bridging both the holiness gap and the gap between mortal and immortal beings.
 ”Hear, O Israel: The LORD our God, the LORD is one.” (Deut. 6:4 ESV)
 The unity of heart and mind (or body, soul, and mind) implies that having a pure heart is a holistic statement of purity—purity throughout our entire person or being. Benner (1998, 22) notes that when the Bible refers to a division of the person, the division is for emphasis, not to infer that the person can be divided into separate and distinct parts.
 The Acts 26 allusion is the most complete: ἀνάστηθι καὶ στῆθι ἐπὶ τοὺς πόδας (arise and stand on your feet; Acts 26:16 BNT) which compares with Ezekiel’s words: στῆθι ἐπὶ τοὺς πόδας (stand on your feet; Ezek 2:1 BGT)
 “For John the Baptist has come eating no bread and drinking no wine, and you say, He has a demon. The Son of Man has come eating and drinking, and you say, Look at him! A glutton and a drunkard, a friend of tax collectors and sinners! Yet wisdom is justified by all her children.” (Luke 7:33-35 ESV)
Bauer, Walter (BDAG). 2000. A Greek-English Lexicon of the New Testament and Other Early Christian Literature. 3rd ed. ed. de Frederick W. Danker. Chicago: University of Chicago Press. <BibleWorks. v.9.>.
Benner, David G. 1998. Care of Souls: Revisioning Christian Nurture and Counsel. Grand Rapids: Baker Books.
Brown-Driver-Briggs-Gesenius (BDB). 1905. Hebrew-English Lexicon, unabridged.