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.