Summary: Believing God is wonderful. But Jesus urged us to do one more thing — to speak the word of faith, to verbalize what we are seeking from God. Such a believer, who understands the power of the spoken word of faith, "shall have whatsoever he saith".
Mark 11:22-23, KJV ...Have faith in God.  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.
We see here three foundation stones of faith that gets results:
(1) Have faith in God [vs. 22] — faith in His Word and in the promises of God, faith in His Son Jesus. It’s not “faith in faith” or in memorized formulas that gets results, but faith in God.
(2) Believe in your heart, without doubting.
(3) And say with your mouth what you believe.
•• Believe in your heart and say with your mouth. Believing God and His Word is of great importance. But Jesus encourages us further to articulate, to say aloud, what we are believing God for. There is great power in the spoken word of faith.
1 John 5:14-15 This is the confidence we have in approaching God: that if we ask anything according to his will, he hears us.  And if we know that he hears us — whatever we ask — we know that we have what we asked of him.
•• We can’t just say any and everything that comes to mind and expect God to grant it. Our saying must be "according to His will". And His will is found in His word, the bible.
•• We can’t say with faith, “Lord, give me seven Rolls Royces, one for each day of the week.” That’s not God’s will for you.
•• We can say with faith, “Lord, I believe that you are Jehovah-Rapha, the Healer of my sickness”, because we find in the bible God’s promises of divine healing. The power of our words, when they are solidly based upon Scripture, is irresistible.
•• We can say with faith, “Lord, through you I can defeat the devil, not be defeated by him”, because we find various New Testament verses declaring Jesus’ defeat of the devil on our behalf.
•• Having thus determined from God’s Word that which is in accordance with His will, we can confidently believe God for these things — and speak these things with our hearts full of faith.
• Hebrews 13:5-6 "...because God has said ... so we say with confidence..." When God has spoken on a subject, that emboldens us to speak forth on that subject. The bible is the word of God Almighty, and His words on our lips have immense power.
Romans 10:8-10 ...“The word is near you; it is in your mouth and in your heart,” that is, the word of faith we are proclaiming:  That if you confess with your mouth, “Jesus is Lord,” and believe in your heart that God raised him from the dead, you will be saved.  For it is with your heart that you believe and are justified, and it is with your mouth that you confess and are saved.
KJV:  ...with the mouth confession is made unto salvation (Greek: soteria).
•• Our mouth confesses unto “salvation” (the Greek word has various biblical meanings):
•• That’s why it’s so important to help new believers pray a “sinner’s prayer”. Help them to confess their newfound salvation with their mouths.
•• If you’re sick, believe God for your healing. And vocalize it! Articulate it! Don't just hold it inside. With the mouth confess faith in God unto healing. There is great power in the spoken word of faith!
• Several decades ago a pastor in Alaska was found to have cancer. Some faithful Christian brothers counseled him to pick three favorite healing verses and speak them often, day after day. He did so and was healed of his cancer and went on to have a long and effective ministry. The spoken word of faith applied the awesome power of God’s Word to the man’s sick body, with spectacular results.
Genesis 1:3 And God said, “Let there be light,” and there was light.
•• And for each of the six days of creation, as recorded in Genesis 1, “God said...” and dramatic creation events occurred.
•• The words that God speaks have unlimited power.
• He spoke the universe into existence!
• For our benefit He has summarized for us a revelation of Himself in 66 books, the Bible. There is immense power in those words in the Bible. Learn them, believe them, speak them.
•• You don’t have to wonder what to believe God for. You’ll find in the bible a wealth of promises to believe God for.
• And then when you find what God’s Word says about your situation, speak the word of faith, as God did in the Creation.
John 6:63 [Jesus said] The Spirit gives life; the flesh counts for nothing. The words I have spoken to you are spirit and they are life.
Proverbs 18:21 The tongue has the power of life and death.
•• Jesus was alive on earth — and full of faith — for 30 years before His Holy Spirit anointing at River Jordan (Matthew 3:16). Then He began to speak forth publicly and confidently His words of faith (Matthew 4:17). Only then did His healings, miracles, and other signs and wonders begin to happen (John 2:11). 30 years ... no miracles or healings. Then (1) the Holy Spirit anointing came upon Jesus and (2) He began to preach, teach, and speak aloud the things of God. And then dramatic healing, miracles, and other supernatural signs began to be manifested. He had become an anointed, faith-filled speaker.
•• The words of Jesus in your mouth are still His words. Therefore, they are still “spirit and life”!
•• Jesus' words and promises spoken by your mouth have the “power of life and death”.Speak life!
Luke 6:45 The good man brings good things out of the good stored up in his heart, and the evil man brings evil things out of the evil stored up in his heart. For out of the overflow of his heart his mouth speaks.
•• The mouth tends to speak what is in the heart. So store the Word of God up in your hearts, and let it overflow from your mouth. Here are some examples of the spoken word of faith coming from a faith-filled heart full of God’s Word.
• “I’m not going to go around afraid of you, devil, because Jesus has given me ‘authority ... to overcome all the power of the enemy’ ” (Luke 10:19).
• “This sickness or infirmity must go, because Jesus Himself ‘took up our infirmities and carried our diseases’ ” (Matthew 8:17).
• “I will not fear an untimely death because God’s Word says, ‘I shall not die, but live, and declare the works of the Lord’ ” (Psalm 118:17, KJV).
• “I’m not going to struggle in poverty all my life, because ‘God will meet all [my] needs according to his glorious riches in Christ Jesus’ ” (Philippians 4:19).
•• Fill your heart with the truths and the promises of God’s Word, then speak them. They will come forth with power and will bring life.
2 Corinthians 4:13 It is written: “I believed; therefore I have spoken.” With that same spirit of faith we also believe and therefore speak.