IF THOU couldst but see [how the deniers of the truth will fare on Resurrection Day,] when they will shrink in terror, with nowhere to escape - since they will have been seized from so close nearby

If thou couldst but see when they will quake with terror; but then there will be no escape (for them), and they will be seized from a position (quite) near.

Couldst thou but see when they are terrified with no escape, and are seized from near at hand,

And couldst thou see when they become terrified, but (then) there will be no escape and they will be seized from a near place;

And if you could see when they are terrified but there is no escape, and they will be seized from a place nearby.