Fork in the road (metaphor)

A fork in the road is a metaphor, based on a literal expression, for a deciding moment in life or history when a choice between presented options is required, and, once made, the choice cannot be reversed.

[1] "Mortal, mark out two roads for the sword of the king of Babylon to come; both of them shall issue from the same land.

And make a signpost, make it for a fork in the road leading to a city; mark out the road for the sword to come to Rabbah of the Ammonites or to Judah and to Jerusalem the fortified.