The word used for "pure" in MAT 5:8 means "to be pure after cleansing." It means "to be without blemish", but also "to be free from mixture." So this characteristic could be described as singular, unmixed cleanness. It is significant that it is described as “pure in heart”. The heart is used metaphorically as the place of our thoughts and desires. The disciple who is pure in heart is one who allows himself to be cleansed from conflicting desires that interfere with his purity of devotion to God. To such a person all of life becomes pure (TIT 1:5), that is, committed to love for, and worship to, God. This type of character is in stark contrast to the “double-minded man” in JAM 1:6-8. The double-minded man kind of believes, but not quite. He desires relationship with God, but also those things that destroy relationship with God. This type of man is never happy. In sin he is convicted of his need for God and in the presence of God he is dissatisfied due to his desire for sin. Jesus, wishing to warn us of this state, says, “Blessed are the pure in heart, for they shall see God”.
How is it that we "see God?" It is clearly not speaking of seeing God in eternity since all who believe in Him will be purified there. Neither does it speak of physical vision since “we walk by faith and not by sight” (2CO 5:7). Jesus speaks of seeing God in the sense of knowing Him, seeing His power and seeing Him active in our lives. He who purifies himself will be aware of God’s presence guiding and keeping him. HEB 12:14 also speaks of holiness that allows us to see God. These concepts of purity and holiness are closely connected. Both carry the idea of having nothing mixed in our purposes and desires. So how can we be purified?
Purifying oneself is an act of faith that states that God’s gift of life includes all of our heart's desires, as such, all of life becomes an opportunity to drink deeply of this God-given life. This does not necessarily mean that our activities will be different. The mundane chores will still be present. It is the heart that must be purified. Rather than changing our activities, we change the motives behind them. We work not to fulfill the desires of our flesh, but to have something to offer to Him who gives us life. We complete the mundane duties of life not as a chore, but as an offering to God; in this way they are no longer mundane--now they are sacred and worshipful. Recognizing that God is the source of all fulfillment, we seek to eliminate in ourselves all that separates us from Him, and seek in each activity and moment to serve Him and discover Him; in all of life, offering back to God something of the worshipful and joyful life that He has given us.