yes, 'so be it' is a form of amen but it is more a command or a "seal" as in approved or sent.
The I AM cult used "decree" as a form of commanding reality according to a "science of the spoken word" that grew out of the New Thought Movement groups that employ froms of commanding reality through "affirmations" or "treatments." Later the Prophets of CUT and others added hand gestures or "mudras" taken from ancient Hinduism. Mudras combined with mantras were especially 'potent' ritual forms in ancient belief systems. Eliz Prophet often used hand gestures to complement her "decrees" as did all CUT members.
In Sanskrit 'mantra' meant 'to cast a spell'. The idea behind this is that to "name" something means to gain power over it. Thus to "name" a god, also meant to grab the god's attention for whatever you ask for, or 'take power over' by identifying with the god with an invocation or mantra.
In ancient Canaanite and Hebrew culture, man was said to "name the animals", thus taking power over them.
By the time of Isaiah, Hebrews claimed that 'sorcery' [witchcraft, mediums] or manipulating the gods through sacrifice and chanting was essentially false or deceptive, did not work, or just plain dumb. yet, the Jews retained an enormous industry in Temple sacrifice of animals until after the time of Jesus and the emergence of the rabbinical period that ended the sacrifices, [as did Christianity through the eternal atonement of God as "Christ Jesus"].
But back to New Thought, which is a form or Protestant religion, Isaiah 45:11 from the Old King James translation has been abused by "name it and claim it" Christian cults [Robert Tilton, eg], Robert Schuler's Crystal Cathedral sect, and the entire "positive thinking" movement.
King James Version (KJV)
11Thus saith the LORD, the Holy One of Israel, and his Maker, Ask me of things to come concerning my sons, and concerning the work of my hands command ye me.
CUT and the I AM used this very quote to 'Biblically' justify casting spells through decrees or to "command" God's energy.
the proper translation
in context is fairly clear, even if you use the clumsy Old King James IF you read the entire section.
a lot of sacred ink has been spilt over this passage,
http://bible.cc/isaiah/45-11.htm
but one only has to read the entire section in Isaiah and it is clear to me at least that G-d thru Isaiah is really saying:
I made you, you little sh*t, how dare you command me to do anything? But you can ask anyway, and I will listen when and if I damn well please. [joe sz translation]
This all boils down to magical thinking that has been pervasive throughout human history and is still incorporated in major religions [power of prayer, etc]. Modernism has been at war with all forms of superstition and magical thinking, especially since the 19th century. Major religions continue to struggle with superstitious trends in ther own ranks that are hard to eradicate.
Most of our modern cults that stem from Fundamentalism in all religions, Theosophy and New Thought continue to buck the Modernist paradigm and try to 'outflank' science with crazy notions and 'proofs' that magical prayer, psychic power [remote viewing] and mantras can "work" on command. RSE like Scientology is just another form of aberrant application of religious ideas.
Us little sh*ts still have a lot to learn from Isaiah, it seems.
so be it