The Ignatius Catholic Study Bible New Testament (261 page)

12:1 cloud of witnesses:
The heroes of biblical history enumerated in Hebrews 11. They are pictured crowded into a stadium, looking down on believers still running the race of faith and urging them on to victory. At the finish line stands Jesus, waiting to reward us (12:2). • Images of the faithful departed cheering us on hints at the communion and intercession of the saints. It shows that the Church in heaven is neither cut off from nor disinterested in the pilgrim Church on earth but is actively solicitous of her salvation (CCC 2683).
every weight:
As a runner sheds whatever might restrict his movements or hamper his performance, so the believer must rid himself of every encumbrance in life that will jeopardize his chances for winning the eternal prize.
run with perseverance:
Life is more like a distance race than a short sprint. Endurance is therefore necessary to keep moving toward the finish without losing faith along the way (10:36). For the comparison between Christian living and athletic competition,
See note on 1 Cor 9:24-27
. 
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12:2 looking to Jesus:
Christ was victorious because he looked beyond the Cross to the crown of glory prepared for him by the Father (2:9). This is meant to encourage readers growing weary in the midst of persecution.
the shame:
Of the Crucifixion.
See note on Mk 15:24
.
seated at the right hand:
The position of the triumphant priest-king of Ps 110:1. 
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12:5-6
A citation from Prov 3:11-12. • The proverb teaches that divine discipline is inspired by divine love. Without this wisdom, one might mistake the trials of life (such as persecution; Heb 10:32-36) for signs of God's anger hammering down on every fault and failure. On the contrary, God is a wise and caring Father who desires only to make his children better. It is because he loves them too much to overlook their sins and selfishness that he sends difficulties to train them in righteousness and to raise them to spiritual adulthood. In point of fact, the sons of God are being forged in the image of God the Son, who "learned obedience through what he suffered" (5:8) (CCC 2825). 
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12:8 illegitimate children:
Those with no rights of inheritance in Roman society. 
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12:9 earthly fathers:
Literally, "fathers of our flesh", which sets up a contrast with God as the Father of spirits. 
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12:12-13
Continuing the race metaphor in 12:1, the author pictures his discouraged readers as a runner slouched over with exhaustion and swerving back and forth along the track. Like a coach, he urges them to summon their energies and charge ahead toward the finish line. • His words allude to the Greek versions of Is 35:3
(drooping hands, weak knees)
and Prov 4:26
(straight paths).
Isaiah encourages the fearful of Israel with news that God is coming to their rescue, and the proverb is a father's instruction to his son to follow the straight and narrow way of righteousness. 
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12:14 Strive for peace:
So far as it depends on the believer, who might be tempted to return evil for evil to his persecutors (Rom 12:14-18).
holiness:
Personal sanctification is required for attaining the vision of God in heaven (Mt 5:8; Rev 22:4). This includes being made holy or sanctified by the grace of God, first of all in Baptism (1 Cor 6:11). However, the Lord also wills us to "strive" for an increase in sanctification by the exertion of our will in living the gospel to the full (Rom 6:19; 1 Thess 3:12-13; 4:3). The text declares this second aspect of holiness to be indispensable for reaching heaven. 
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12:15 root of bitterness:
Someone who spreads discouragement and doubt among believers. Readers must guard against anyone having such an evil influence on others. • The expression comes from Deut 29:18, where it refers to an idolater who leads Israel away from the Lord. 
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12:16 Esau:
Despised his birthright and traded it in for momentary pleasure. • Esau, being a first-born, was entitled to the blessings of the Abrahamic covenant that passed through the line of Isaac (Gen 22:16-18; 26:1-5). However, he relinquished this inheritance when he exchanged his birthright for a mere meal (Gen 25:27-34), and though he later regretted his losses, he was never able to recover them (Gen 27:30-40). This tragedy stands as a warning for readers, who share in the blessings of the Abrahamic covenant (Heb 6:1318) but who are tempted to relinquish their faith for temporary relief from persecution. 
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12:18-24
The Old Covenant is contrasted with the New: they are represented by different mountains (Sinai/Zion), different assemblies (Israel/Church), different responses (fear/ worship), different locations (earth/heaven), and different mediators (Moses/Jesus). The author is launching his final appeal to keep readers from sliding back into Judaism. See introduction:
Destination and Purpose.
 
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12:18-21
Israel's experience at Mount Sinai. • What
may be touched
refers to the mountain itself as the Lord descended upon it with a dramatic display of fire and smoke and blaring trumpets (12:18; Ex 19:16-20; Deut 4:11). Terrified by this, the people begged to hear
no further messages
directly from Yahweh after he had uttered the Decalogue in a thunderous voice (12:19; Ex 19:19; 20:18-20; Deut 5:4). No man or
beast
was permitted to touch the mountain (Heb 12:20; Ex 19:12-13) except for Moses, who later admitted to trembling
with fear
(Heb 12:21; Deut 9:19). 
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12:22-24
The celestial liturgy of heaven, where angels and saints are gathered to worship God and to celebrate the redeeming work of Christ (Rev 4-5; 7:9-17; 14:1-5; etc.). Readers are invited to join in this eternal liturgy (Heb 12:28) by entering the heavenly sanctuary through prayer and sacramental worship (10:19-22) (CCC 2188). 
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12:22 Mount Zion:
The heavenly summit (Rev 14:1) whose counterpart is the earthly mountain where Jerusalem has stood for centuries (Ps 76:2; Is 2:3).
heavenly Jerusalem:
Alluded to earlier as the city whose foundations were laid by God in eternity (11:10, 16). Other passages refer to this as the Jerusalem "above" (Gal 4:26) and the "holy city" from heaven (Rev 21:2, 10). 
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12:23 the assembly:
Or, "the Church".
the first-born:
The saints in heaven (the Greek is plural) united with Christ the first-born Son (1:6).
enrolled:
I.e., registered by name in the heavenly Book of Life (Lk 10:20; Rev 21:27).
spirits of just men:
Perhaps the righteous men and women of OT times who were perfected by Christ (11:40) and led into heaven (Eph 4:8). Like all the faithful departed, only their "spirits" are present with God as they await the resurrection of their bodies at the end of history (1 Cor 15:51-55). 
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12:24 blood that speaks:
The spilled blood of Abel cried out for vengeance (11:4; Gen 4:10), but the sprinkled blood of Jesus calls for forgiveness and peace (Heb 9:12; Col 1:20). 
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12:25
The argument that a greater message lays greater responsibility on the hearers also appears in 2:1-3 and 10:2829, where the same contrast is made between the Law of Moses and the gospel of Christ. 
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12:26 shook the earth:
Mount Sinai quaked and rumbled in the presence of God (Ex 19:18; Ps 68:8). 
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12:26 Yet once more:
A citation from Hag 2:6. • Haggai speaks in apocalyptic terms about a dramatic intervention of God to overthrow the kingdoms of the earth (Hag 2:2122). The point here is that God is about to shake "the world" of the Old Covenant to the ground, so that only the unshakable kingdom of Christ will be left standing amidst the rubble (Heb 12:28).
See note on Heb 8:13
and essay:
End of the World?
at Matthew 24. 
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