Jesus frequently spoke to problems, commanding them to submit to God's will. He cast out demons with words. He commanded sickness to leave. He spoke peace be still to the wind and waves during a terrifying storm while in a small boat on the Sea of Galilee. Jesus told us, if we speak to the mountain, whatever it is in our lives that we need to have removed and believed God would remove it for us.
That's in Mark 11:23. When we declare scripture, we're speaking to the mountain, the lie that needs to be removed from our lives, and we're declaring God's word. And God does. He removes it. The lie. He establishes the truth. He establishes the truth and replaces the lie.