Hebrews 6 is the center of much theological debate. What makes the passage difficult to interpret is that the author seems to couples two contradictory ideas together: true believers and “falling away.”
This warning actually begins in 5:11. The author turns aside from the topic of Melchizedek because of the spiritual immaturity of his audience. In 6:4-5, the author uses four descriptions of the persons in this case: 1) “enlightened,” 2) “tasted the heavenly gift,” 3) “shared in the Holy Spirit,” 4) “tasted the goodness of the word of God and the powers of the age to come.” These descriptions must refer to true believers—a point not disputed among scholars.
The phrase “fallen away” presents a difficulty because the word and the warning that follows are severe. If one falls away, he cannot be restored. Also, English gets the word “apostatize” from this Greek word. The term in Greek simply means to fall down or to follow the wrong path. Thus, the picture is similar to “drift away” in 2:1.
Instead of salvation, this passage concerns spiritual maturity (5:12). If this passage were discussing salvation, then one who fell away from salvation cannot regain it. The believer who has fallen away cannot go back to the beginning and start his Christian life over (cf. 6:1 and 6:6). The consequences from his lack of attention to spiritual things cannot be reversed or undone. Esau sought the birthright with tears, but could not get it back (12:17).
The illustration that follows describes that although the believer is blessed by God, he can use those same blessings to live ungodly. A believer who does so should expect judgment and not continued blessing.