Are Silent Prayers Effective in Rebuking Satan?

Any silent prayer can be efficacious, precisely because God can read our thoughts and respond accordingly.

As with spoken prayers, though, God may allow us to be tested to cultivate greater faith and other virtues in serving him, and thus we shouldn’t be discouraged if a trial of whatever sort endures longer than we would like (Rom. 12:12; see Luke 18:1-8; 1 Pet. 5:6-7).