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baptism by fire

n. 1 (context idiomatic English) A rite of passage through the survival or success of a crisis. 2 (context idiomatic English) A trying ordeal that was not experienced before. 3 (context idiomatic English) A change in initial attitude or ideals through a traumatic situation.

Wikipedia
Baptism by fire

The phrase baptism by fire or baptism of fire is a phrase originating from the words of John the Baptist in Matthew 3:11. The phrase also occurs in Luke 3:16 and it might be taken as a reference to the fiery trial of faith which endures suffering and purifies the faithful who look upon God's glory and are transformed, not consumed (Mark 10:38, James 1:2-4, 1 Peter 1:7, 1 Peter 4:12). See also Dante's Purgatory 27:10-15.

Usage examples of "baptism by fire".

I reminded myself that Billy and the Alphas had already had their baptism by fire, and they'd had almost two years to hone their skills against some of the low-intensity riffraff of the Chicago underground scene.

Perhaps its the inevitable result of a baptism by fire like a Freeing.

Perhaps it's the inevitable result of a baptism by fire like a Freeing.

But after graduating next year, young Evan is heading straightaway to law school, his resume jazzed by a semester of working journalism once viewed as a baptism by fire, but these days regarded more as an act of exotic self-sacrifice.

He'd got his baptism by fire against the black rebels in Georgia in 1916, before his division went to fight the damnyankees in Texas.

I reminded myself that Billy and the Alphas had already had their baptism by fire, and they’.