“The Greek word rendered “jealous” is the origin of the English word “zeal.” It means “jealous,” but also means “to strive after,” “eagerness,” and “admiration…Christians are (1) called to follow Christ with enthusiasm and zeal (Acts 18:25; Rom 12:10, 11) and (2) warned against misguided enthusiasm, a zeal “not according to knowledge” (Rom 10:2).” (Orthodox Study Bible, Zechariah 1:14-15, Glossary)
“Love does not preclude a zeal for the beloved or a protective, positive, proper jealousy. God is jealous for His people against all falsehood that destroys His creation…God's zeal is a protective love that does not wish to see His people degraded and harmed.” (Orthodox Study Bible, Zechariah 1:14-15, 8:1-3)
“Zeal is great ardor or enthusiasm for a cause, characterized by energetic action toward the realization of one’s desired goal. Zeal is not necessarily virtuous: there is holy zeal, but also ardor combined with action not in accord with God’s will. Only zeal grounded in knowledge that embraces God’s will (Rom 10: 2-3) fully accords with the Lord’s purpose and methods.” (Dynamis 10/9/2019)
“ ‘My heart’s desire and my supplication to God is for Israel, that they may be saved. For I bear them witness that they have a zeal for God, but not according to knowledge. For being ignorant of God’s righteousness, and seeking to establish their own righteousness, they did not submit to the righteousness of God’ (Romans 10:1-4)…People have a zeal, but it is not a zeal ‘according to knowledge.’…We are all sacrificing all the time. We give over our praise, our possessions, our time and our words to various pursuits and desires. But so much of the time, we do so with a zeal that is not according to knowledge, the knowledge of the true God. We are sacrificing instead to other gods, and we are becoming like them, not just in the ways that seem attractive but also in the ways that are dark and broken.” (Father Andrew Stephen Damick)
“Jesus cleansed the temple from the sellers and money changers and ‘then His disciples remembered that it was written, “Zeal for Your house has eaten Me up’ (John 2:17)… show zeal for God. Let zeal for God search you through, and devour you, so that each one of you may say, ‘The zeal of Thine house hath eaten me up’…This is true zeal for God—to know Him and love Him with a deep and consuming love, and to serve others in the same way we would serve Jesus. Anything else is an imitation.” (Sacramental Living Ministries, St. Ambrose of Milan, Keith Green)