What did Jesus mean by "pure in heart" in Matthew 5:8?

Question

Matthew 5:8 (KJV):

8 Blessed are the pure in heart: for they shall see God

What did Jesus have in mind when he said "pure in heart"? What qualifies as being "pure in heart"?

Answer 1

Pure

The root word is καθαρός (katharos), meaning:

clean, pure, unstained, either literally or ceremonially or spiritually; guiltless, innocent, upright...unmixed (see here)

The heart - the thinking organ

To the ancient Jews, the heart was the thinking organ.

Claude Tresmontant observed in his commentary on Deut. 6:

When we translate literally the Hebrew be-kol lebabeka as 'with all you heart,' we evidently cannot be faulted too badly. After all the Hebrew leb does mean 'heart.' Nevertheless because the 'heart' was considered by the ancient Hebrews to be the organ of the intelligence and not of affectivity, we fail to render the true meaning of the sentence when we translate leb literally. To love with all one's heart for us it to love with very great emotion and affection; understanding this command in that fashion, we are unlikely to realize that we were really commanded in this passage to love God with all our mind or intelligence. (The Hebrew Christ p. 190)

What you see is what you get

In the Jewish culture in which Jesus taught & Matthew wrote, "pure in heart" would call to mind (no pun intended) sincerity in thoughts or intentions--these things are not contaminated with sin or mixed with ulterior motive.

To use a modern expression, a person who is pure in heart is not two-faced; they are the same person in public as they are when they think nobody is watching.

Answer 2

The operative word, pure, in Matt 5:8 has come directly into English as catharsis - a purifying and purging. According to BDAG, καθαρός has the following meanings:

1. pertaining to being clean and free from adulterating matter, clean, pure, eg, Matt 23:26, 27:59, Rev 15:6, etc.
2. pertaining to being cultically/ceremonially pure, ritually pure, eg, Rev 14:20, Tit 1:15ac.
3. pertaining to being free from moral guilt, pure, free from sin, eg, (a) of persons: Tit 1:15b, John 13:10, 11, 15:3, Matt 5:8, Acts 18:6, 20:26, etc
4. pertaining to being pure ritually and morally, pure, eg, Luke 11:48.

Thus, by this lexicon, being "pure in heart" is to be morally pure and free from sin. This is an attribute that we are encouraged in imitating Christ:

• Be pure as He is pure. 1 John 3:3. [albeit using a different word in Greek]

Ellicott suggests this:

(Matt 5:8) Pure in heart.—Here, as with the poor in spirit, the noun determines the region in which the purity is to be found—the “heart” as representing desires and affections, as the “spirit” represents the will and higher personality. The purity so described is not that which was the ideal of the Pharisee, outward and ceremonial, nor, again, was it limited, as the common language of Christians too often limits it, to the absence of one special form of sensual sin; but it excluded every element of baseness—the impurity of hate or greed of gain, no less than that of lust. Not without cause, however, has the evil of the latter sin so overshadowed the others that it has almost monopolised the name. No single form of evil spreads its taint more deeply than that which “lets in contagion to the inward parts.”

Meyer is more succinct:

Matthew 5:8. Οἱ καθαροὶ τῇ καρδίᾳ] denotes the moral blamelessness of the inner life, the centre of which is the heart

Barnes add something else:

Blessed are the pure in heart - That is, whose minds, motives, and principles are pure; who seek not only to have the external actions correct, but who desire to be holy in heart, and who are so. Man looks on the outward appearance, but God looks on the heart.