Gilgal
Gilgal signifies the doctrine of natural truth serving as an introduction into the church.
(References: Apocalypse Revealed 700)
Apocalypse Revealed #699
699. 16:12 Then the sixth angel poured out his bowl upon the great river Euphrates. This symbolizes influx from the Lord into the people's interior reasonings by which they defend justification by faith alone.
The sixth angel's pouring out his bowl symbolizes, here as before, influx. The great river Euphrates symbolizes interior reasonings, the same as before in nos. 444, 445, here the interior reasonings of the Protestant Reformed church which they use to defend justification by faith alone, because this is the subject in the verses that follow next.