An overseer, then, must be above reproach, the husband of one wife, temperate, prudent, respectable, hospitable, able to teach…
1 Timothy 3:2 (emphasis mine)

Nēphalios (temperate) literally means wineless, or unmixed with wine.1

In a metaphorical sense, nēphalios means alert, watchful, vigilant, or clear-headed. That may be its primary sense in this passage. A leader must be one who thinks clearly. He must possess the inner strength to refrain from any excess that would dull his alertness.2

This specific word is also used in relation to other believers who are not elders:

Women must likewise be dignified, not malicious gossips, but temperate, faithful in all things.
1 Timothy 3:11 (emphasis mine)

Older men are to be temperate, dignified, sensible, sound in faith, in love, in perseverance.
Titus 2:2 (emphasis mine)

The overseer is to maintain command of his reason, to be watchful and observant of things going on around him, and balanced in his assessments.3

To be temperate shows that the church leader had to be free from rash actions. The word describes self-control with regard to use of intoxicants, but it can also be used to describe a mental self-control that rules out all forms of excess. Paul dealt with the use of alcohol in 3:3. He was not covering this same subject here. Paul’s term here referred to someone who was sober and balanced in spirit.4

 

1 MacArthur, J. F., Jr. (1995). 1 Timothy (p. 105). Chicago: Moody Press.
2 MacArthur, J. F., Jr. (1995). 1 Timothy (p. 106). Chicago: Moody Press.
3 Towner, P. H. (2006). The Letters to Timothy and Titus (p. 251). Grand Rapids, MI: Wm. B. Eerdmans Publishing Co.
4 Lea, T. D., & Griffin, H. P. (1992). 1, 2 Timothy, Titus (Vol. 34, p. 110). Nashville: Broadman & Holman Publishers.