A zealous person in Christianity is preeminently a person of one thing. It is not enough to say that they are earnest, strong, uncompromising, meticulous, wholehearted, and fervent in spirit. They only see one thing, they care for one thing, they live for one thing, they are swallowed up in one thing; and that one thing is to please God.
Whether they live, or whether they die-whether they are healthy, or whether they are sick-whether they are rich, or whether they are poor-whether they please man, or whether they give offense-whether they are thought wise, or whether they are thought foolish-whether they are accused, or whether they are praised-whether they get honor, or whether they get shame-for all this the zealous person cares nothing at all.
They have a passion for one thing, and that one thing is top please God and to advance God’s glory. If they are consumed in the very burning of their passion for God, they don’t care-they are content. They feel that, like a candle, they were made to burn; and if they are consumed in the burning, then they have only done the work for which God has appointed them. Such a person will always find a sphere for their zeal.
If they cannot work, or give money, or a man cannot preach, then they will cry out and sigh, and pray. Yes: if they are extremely poor, on a perpetual bed of sickness, they will make the activity of sin around him slow to a standstill, by continually interceding against it. If they cannot fight in the valley with Joshua, they will do the work of Moses, Aaron, and Hur, on the hill. (Exodus 17:9-13) If they are cut off from working themselves, they will give the Lord no rest until help is raised up from another quarterand the work is done. This is what I mean when I speak of zeal in Christianity.
J.C. Ryle (1816-1900) by way of David Platt, "Zealous for one thing" Sermon