Some of the most stringent atheists are those raised religious who felt betrayed by the dogma or how they were raised.

Or those who have tragically lost loved ones and thought God should have saved them. God gave up his only Son, letting enemies kill Him on a cross. We cannot fathom the reasons why, but just because we have lost someone doesn't mean God has forgotten or abandoned them. IMO, Matthew 10:29 says it best:

Οὐχὶ δύο στρουθία πωλεῖται ἀσσαρίου; καὶ οὐ ἓν ἐξ αὐτῶν πεσεῖται ἐπὶ τὴν γῆν ἄνευ ὑμῶν Πατρὸς.

"What is the price of two sparrows—one copper coin? But not a single sparrow can fall to the ground without your Father knowing it."