I have come across many Christians who attempt to make a case against public and/or corporate prayer based on Matt. 6:6 which says, “But when you pray, go into your room, close the door and pray to your Father, who is unseen. Then your Father, who sees what is done in secret, will reward you.”
This is a general principle that someone has improperly tried to turn into a legalistic rule. Otherwise how could you have a laying on of hands for healing (James 5:16) or two or three agreeing to something in prayer (Matt. 18:19), or dedication ceremonies? Jesus was preaching against the Pharisees who uttered long and impassioned public prayers, solely for the purpose of showing off their “piety.” There are times where public prayer is not only permissible but preferable.