The word that we often translate as "devotion" "piety" "religion (as virtue)" actually means something more. It designates a lifestyle that is grounded in the ways of the Lord and is expressed in loyalty, kindness, generosity and righteousness.
Liddel and Scott gives four meanings for the Greek word "eusebeia":
1. reverence for the gods and for one's parents
2. loyalty
3. Latin "pietas"
4. the character of piety
For the greeks of classical antiquity then the word that we often translate as "devotion" and "piety" designate attitudes towards god and men.
When the OT Scriptures was translated into Greek, "eusebeia" was used as the equivalent of yir'ah (fear, reverence) and yir'at Yahweh, "fear of the Lord. (e.g. Isaiah 11:2)" A related word "eusebes" (devout, pious) also appears in the LXX as the equivalent of three Hebrew words:
1. Hasid -- the devout, those who are dutiful towards Yahweh and who are kind towards their fellow-men.
2. Nadib -- the noble ones, those who are generous and kind.
3. Zadiq -- the righteous, the just one, those who live according to the torah of the Lord.
In the NT, "eusebeia" appears mostly in 1 and 2 Timothy, Titus and 2 Peter. In 1 Tim. 2:2, "devotion" appears paired with "dignity" and may express the meaning of "nobility." However, in 1 Tim. 3:16, the "mystery of devotion" is actually the kind of attention and generosity that God shows to mankind in Jesus Christ. Because of God's devotion, there is also an ascending devotion towards him coming from man which is expressed in "training in devotion" (1 Tim. 4:7). This latter is translated as "exercitium pietatis" in the Latin Vulgate, which in English came to be taken as "exercise in piety." However, the usage in 1 Tim 4:7 does not have the "mushy" connotation that the phrase "exercise in piety" currently has. The "training in devotion" mentioned there includes the adherence to truths of religion revealed in Christ and proclaimed by the apostle (1 Tim. 6:3ff; Tit 1:1). All true devotion comes from God (2 Pet 1:3). To persevere in the faith, one must have a devotion that is tempered by mutual affection (2 Pet. 1:6). Finally, in 2 Pet 3:11, "devotion" is paired with "holiness", indicating a life-style that is conformed to the ways of the Lord.
