Is visualization technique an act of faith or sorcery?
You would call it an act of faith because God who calls things that are not as though they were; he speaks the Word and it happens or in other words is created. So God placed this ability in the spirit of man who is in all ways made in God's image and also knows God's power through faith.
You would call it magic because it is one of the fundamentals of conjuring, incantations and spells. It is of