Our words have power
Take this statement however you will. From one end of the spectrum that says that we literally create via positive (or negative) affirmation, the things we wish to see and possess and encounter (somewhat mystical/New-Agey in tone). To the other end that looks at words and language as merely a symbolic representation of intangible and inchoate thought-forms resident in the brain's language centers (Broca's and Wernicke's Areas) and nothing more--a view more in line with a hardened scientific-materialism. I'd have to say that I'm somewhere in the middle. Words are amazing and yet, how many of us use our words to the best of our advantage and to the validation of others? Which, I'd have to say, is one of their chief aims. Words, that is.
I read this statement of Jesus: "For verily I say unto you, That whosoever shall say unto this mountain, Be thou removed, and be thou cast into the sea; and shall not doubt in his heart, but shall believe that those things which he saith shall come to pass; he shall have whatsoever he saith." (Mark 11:23, emphasis mine) And it makes me think and wonder. Do I literally have to speak certain things out? I mean, out loud into the air? As I am, at times, somewhat of an introvert, the idea of a personal God that dwells inside of me, that hears the tiniest thought I choose to direct to Him in the silence of my heart, is appealing. It's not about whether or not being introverted is right or no, it's about a fluid living-by-faith where the things we do are resonant with the words Jesus spoke and the timing and leading of the Holy Spirit. Conversely, to never be willing to speak up, or to say something because we've acquiesced and capitulated to a shyness that isn't who we are and are meant to be, I think, is a wrong position.
"Moving mountains." That's what He said. He told me that if I so much as speak to the mountain, provided I don't doubt, it'll go to the sea. It'll cease being the hindrance it was, in other words. As an aside, I see a subtle symbolism in referring to Mt. Zion, "which cannot be removed" it says in Psalm 125 (verse 1). It's almost like Jesus was already challenging the existing Judaic model, as He was wont to do. I digress.
He continues on, seeming to move more inward, into the arena of silent prayer before God (Mark 11:24): "Therefore I say unto you, What things soever ye desire, when ye pray, believe that ye receive them, and ye shall have them." Read together it would seem that they two go hand in hand. And indeed it was that way when we first accepted Him into our lives as Savior:
"That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised Him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation." (Romans 10:9-10, emphasis mine) So there's merit in both approaches. And with such a seismic and monumental event as our very salvation, doing it both ways, says Paul, is required. So, it would seem, does the moving of whatever mountain hinders our walk with God.
Our belief has power
I look at belief as the smallest increment of the doing of a thing. The intention, the impetus of a project, an event, an action, begins in the heart and/or mind. And it begins with belief ("I believe this'll turn out"). Only a fool would actively doubt the things they're choosing to do. There's a lot to that, but I believe that's what it boils down to. But with reference to our words, read this statement of John (the beloved disciple, all grown up--he was in his late teens when he hung out with Jesus and the rest of His disciples): "My little children, let us not love in word, neither in tongue; but in deed and truth." (1 John 3:18) Active belief must be present in order to both speak the words that build up our brothers and sisters (he's not saying to not speak), or remove the mountains in our paths. And for Christians, moving on from simple speaking to actively doing (as in volunteering and ministering and evangelizing from a pure motive) necessarily requires belief in Jesus for it to be rooted in the reality of faith.
"For which of you, intending to build a tower, sitteth not down first, and counteth the cost, whether he have sufficient to finish it? Lest haply, after he hath laid the foundation, and is not able to finish it, all that behold it behind to mock him, Saying, This man began to build, and was not able to finish." I suppose the same could be said for those who sought to erect the Tower of Babel (See Genesis, chapter 11) and for whom we have to thank for the different languages we speak. Jesus continues: "Or what king, going to make war against another king, sitteth not down first, and consulteth whether he be able with ten thousand to meet him that cometh against him with twenty thousand?" (Luke 14:28-31)
In other words, the inner working-out of that which you do begins in the heart and mind. To where the unformed is given form--the form of words. Which in turn, spoken out, create the invisible scaffolding and constructs to begin bringing out God's plans and purposes in this earth. This is the essence of faith. Faith that moves mountains and takes kingdoms.
"A language is a dialect with an army and a navy." Max Weinreich