The First Warning
As mentioned previously, the writer will pause throughout his exposition to address his readers in a series of five urgent warnings. This is the first of such warnings and is the briefest and most restrained of them all. It is nonetheless solemn.
Implications of Previous Teaching
The word therefore connects this admonition to the previous discussion. Because of the Son’s greatness and destiny of victory [over all of His enemies], the readers [which includes us] should give the most utmost attention to what they have heard – and beware of drifting away [from these truths].
He reminds his readers of the Old [Mosaic] Covenant - which was instituted through angelic administration- that there were severe penalties for infractions. Thus, under the New Covenant it should NOT be surprising that retribution will be forthcoming - if we disregard so great a salvation [deliverance].
Of course, Jesus, while on earth, spoke much about His future kingdom and the participation of His faithful followers in that kingdom. But this salvation [deliverance] experience had also received confirmation through the various miracles and manifestations of the Holy Spirit given to His followers right after His ascension. The writer regarded these as powers of the world to come.
 The others are found in Chaps 3-4, 5:11-6:20; 10:19-39; and chap 12.
 Verse 1. The language is very powerful in the original. The readers were characterized by immaturity and spiritual sluggishness (Cf. Heb. 5:11-12) and thus could easily “drift away” from these truths. See Proverbs 3:21 where this same Greek word is used. It reads [in the Septuagint] “My son, do not drift away, but keep my counsel and intent [way of thinking]”.
 See Gal 3:19.
 Verse 2.
 Which is mentioned prominently in this epistle [Cf. Heb. 8:8, 8:13, 9:15, 12:24 etc.]
 Verse 3a. This, of course, is the salvation = deliverance mentioned in Heb. 1:14 concerning the King’s triumph over His enemies. This victory would also be crucial for those sharing this victory [His companions (Heb. 1:9)] who will inherit this deliverance. Note that the author [by using the word we] includes himself.
 Verse 3b. Also note Luke 12:31-32; 22:29-30; 19:11ff, Matt. 24:45-50,;25:14-30 etc.
 Verses 3c-4. These signs, wonders, and miracles were characteristic of the Apostles in the book of Acts [Cf. Acts 2:43; 4:30; 5:12; 6:8 etc.]. They regarded these miracles as expressions of the sovereignty of the One who had gone to sit at God’s right hand [Cf. Acts 2:33; 5:31; 7:55 and Mark 16:19-20 and, of course Heb. 1:3].
 See Heb. 2:5; 6:5.