What was the greatest revival ever?

Pentecost yielded 3000 souls. Hallelujah! However, the harvest of souls will be even greater during the Tribulation. (Rev 7:9-10, 13). Hallelujah again!

Was it The Great Awakening? That revival, in three waves, yielded thousands over three waves, (First c. 1730–1755; Second c. 1790–1840); Third c. 1855–1900), but Jonathan Edwards worried that some of those in the frenzy were simply carried away by emotionalism and societal pressure rather than their own brokenness over sin, marking them as false converts. In response to the very real probability that mixed in with the genuinely converted were many false professors, he wrote The Distinguishing Marks of a Work of the Spirit of God.

Revivals have always been plagued by errors in judgment from leaders and participants alike, Edwards warned, and have suffered from the delusions of Satan. Great care and discernment are always the order of the day. ~God’s Spirit or Human Hysteria? My Time Among the Charismatics, by Jeff Robinson. So it's hard to count that revival's numbers and thus its effects.

So what was the greatest revival ever? For sure?

It was Nineveh that yielded 600,000 souls for the glory of God. It was and still is the largest harvest God has effected to date. In addition, we know that was a genuine repentance and coming to faith, because first, the Bible said so, and second, the LORD stayed His hand in destroying the city. (Jonah 3:5, 10).

How do we know it was around 600,000 souls when the only number mentioned in regards to Nineveh is 120,000? Jonah 4:11 says,

And should not I pity Nineveh, that great city, in which there are more than 120,000 persons who do not know their right hand from their left, and also much cattle?

'Not knowing the right hand from the left' is a Hebrew idiom meaning 'children'. Children don't know their right hand from their left. Extrapolating the number of children and assigning them to two parents, historians and theologians estimate the city was populated by about 600,000. Its size also (three days' walk) indicates a populous, bustling city of this magnitude.

By comparing these revivals at Pentecost, Nineveh, and the Tribulation we can praise God for His continuing and marvelous ongoing work in salvation. We will have lots of company in heaven! As Jonah said, "Salvation belongs to the Lord." (Jonah 2:9). He will glorify His name by His mighty power to deliver men from the darkness of bondage to sin, speaking life into their dead bones,and resurrecting them to eternal life. Praise the Lord!