If you've spent any time in a black church, you've heard Matthew 18:20 thrown about...
"For where two or three are gathered together in My name, I am there in the midst of them."
..but, as usual with the whole Charismatic thing, you have to do your research when somebody throws scripture at you as it is probably being used to excuse heretic foolishness.
FROM GOTQUESTIONS.ORG:
"There is nothing in Scripture to suggest that corporate prayers are
“more powerful” than individual prayers in the sense of moving the hand
of God. Far too many Christians equate prayer with “getting things from
God,” and group prayer becomes mainly an occasion to recite a list of
our wants. Biblical prayers, however, are multi-faceted, encompassing
the whole of the desire to enter into conscious and intimate communion
with our holy, perfect, and righteous God. That such a God would bend an
ear to His creatures causes praise and adoration to pour forth in
abundance (Psalm 27:4; 63:1-8), produces heartfelt repentance and
confession (Psalm 51; Luke 18:9-14), generates an outpouring of
gratitude and thanksgiving (Philippians 4:6; Colossians 1:12), and
creates sincere intercessory pleas on behalf of others (2 Thessalonians
1:11; 2:16).
Prayer, then, is cooperating with God to bring about His plan, not
trying to bend Him to our will. As we abandon our own desires in
submission to the One who knows our circumstances far better than we
ever could and who “knows what you need before you ask” (Matthew 6:8),
our prayers reach their highest level. Prayers offered in submission to
the Divine will, therefore, are always answered positively, whether
offered by one person or a thousand.
The idea that corporate prayers are more likely to move the hand of God
comes largely from a misinterpretation of Matthew 18:19-20, “Again, I
tell you that if two of you on earth agree about anything you ask for,
it will be done for you by my Father in heaven. For where two or three
come together in my name, there am I with them.” These verses come from a
larger passage which addresses the procedures to be followed in the
case of church discipline of a sinning member. To interpret them as
promising believers a blank check for anything they might agree to ask
God for, no matter how sinful or foolish, not only does not fit the
context of church discipline, but it denies the rest of Scripture,
especially the sovereignty of God.
In addition, to believe that when “two or three are gathered” to pray,
some kind of magical power boost is automatically applied to our prayers
is not biblically supportable. Of course Jesus is present when two or
three pray, but He is equally present when one believer prays alone,
even if that person is separated from others by thousands of miles.
Corporate prayer is important because it creates unity (John 17:22-23),
and is a key aspect of believers’ encouraging one another (1
Thessalonians 5:11) and spurring one another on to love and good deeds
(Hebrews 10:24)."
