Mat 5:8 Blessed are the pure in heart: for they shall see God.
Lucky [are] those who free from debts of passion or purely passionate because they are going to see for themselves visions of the divine.
The sense of the Greek word translated as "blessed" shifts its meaning among "happy", "wealthy", and fortunate depending on the context. "Fortunate or lucky seems to work here. This word only means "blessed" in the sense that the lucky are blessed by good fortuned. It is not a religious term.
There is no "is" here. It is added to make a written sentence as opposed to a spoken phrase.
The Greek word translated as pure means free from that which corrupts or soils. There is a hidden connection to the previous verse, Mat 5:7. The merciful are those that forgive debts and one meaning of "the pure" is someone who is debt-free. Though it is hidden, in the Greek these two beatitudes can be seen the two sides of the same coin.
This purity is "of the heart", where "the heart" is in the possessive form. This form has a number of different uses in Greek. Here, the only one that works identifies the producer or the nature of that purity. Christ consistently uses the Greek term to refer to the heart as the seat of emotions. In Greek, these were the strong, passionate emotions. So one sense of this phrase is people who are unsullied or free from the debts created from their passions. For more about the role of this word in Christ's view see this article.
Again, the use of the pronoun for the subject "they" emphasizes it, since the pronoun is already part of the verb ending.
The Greek word for "see" used here primarily means seeing with the eyes or using to eyes, for example, to aim at something. The base of this word is the Greek term for the eye. However, it is also a metaphor for mental perceptions, but perceiving with the mind and to experience. It is also a term used to refer to seeing visions. The case of this verb is the "middle" form which is both active and passive. This means that it sees something, but it is affected by that sight. This works well with the idea of seeing visions, especially with seeing visions of the divine.
There are a number of patterns in the Beatitudes, which are discussed in this article on the Beatitudes.
The term "purity of the heart" can mean both being free from the debts of passion and being completely controlled by passion.
The Spoken Version:
The smiling teacher quickly made his way toward a group of prostitutes. They were seated near the tax collectors and other detestables. Two of these women were clearly pregnant.
“Lucky!” The teacher announced, taking these soon-to-be mothers by the hand. He had them stand so the crowd could see them. The women blushed. “The pure!” He said.
While many laughed, others registered their objections.
“Of heart!” The speaker amended touching his own heart. “For they themselves, are going to see—.” He laid his hands on their large bellies and said, “The divine!”
οἱ καθαροὶ (adj pl masc nom) "Pure" is from katharos, which means "physically clean", "spotless", "clear", "pure (water)", "clear of objects", "free of contamination", "clear of debt", "genuine", "pure of birth", "without blemish," and "sound."
τῇ καρδίᾳ, (noun pl fem nom) "Of heart" is from kardia, which means "heart (the physical organ)", "the seat of emotions (especially passion, rage, and anger)", "inclination", "desire," "purpose", "mind", "the pith (in wood), and "the deep (of the sea)."
αὐτοὶ (adj pl masc nom) "They" is from autos, which means "the same," and the reflexive pronouns, "myself", "yourself", "himself", "herself", "itself," or the oblique case of the pronouns, "him", "her," and "it." It also means "one's true self," that is, "the soul" as opposed to the body and "of ones own accord."
ὄψονται (3rd pl fut ind mid) "Shall see" is from optanomai, which means "to see", "to look", "to aim at", "to look towards", "to have sight", "to take heed," (in transitive) "to behold", "to perceive", "to observe", "to look out for," and "to be seen (passive)." It is a metaphor for mental sight, "to perceive", "to discern", "to see visions", "to appear in visions (passion), and "to interview."