God is the Father of precipitation, Job says (Job 38:25-30). Rain is filial, the Father’s nourishing gift to the world.
The same imagery appears elsewhere. The righteous king is “like rain upon the mown grass” (Psalm 72:6), and the king’s “favor is like a cloud with the spring rain” (Proverbs 16:15). Yahweh “rained down manna upon [Israel] to eat . . . He rained meat upon [Israel] like dust” (Psalm 78:24, 27), and we know that the rain of manna pointed ahead to the true Bread that would fall from heaven (John 6).
Jesus knows what He’s talking about when He says that the generous Father “sends rain on the righteous and the unrighteous” (Matthew 5:45), because He is the rain that rains down upon all Israel. As always, the results are mixed: When Jesus falls from heaven onto the ground of Israel, it produces “vegetation useful for those for whose sake it is tilled” but also thorns, ultimately a crown of thorns (Hebrews 6:7-8).
And if we talk about filial rain, we must also talk about the wind that drives the rain.
“Hey, ho, the wind and the rain. The rain it raineth everyday”: Shakespeare spoke more theologically than he knew.