Our mouth should never say anything different than what God says about us. Every time we do, we contradict God. We basically speak unbelief.
The New Creation makes us sons of God. We are no longer of this world. We have changed passports. We belong to a different Kingdom. And as such, we are now representatives of the Living God on earth.
We are crucified with Christ. In other words, we are supposed to be dead, in our emotions, in our formal thinking, and matters of the heart, etc. We have to take on the new identity that God has given us, every day.
Speaking out the Word of God over ourselves is very important. It’s part of the process of mind renewal (ROM 12:1). We must speak the things that God says about us to ourselves.
Our body is essentially 70% water, and water retains words. Water has memory. Everything that God created responds to words. And our body, our mind, respond to our words. And words must be said out loud, otherwise, they’re just thoughts.
Your thoughts also affect your destiny but it is your tongue that is the rudder to your boat (James 3:1-12). According to Proverbs 18:21, “The tongue can bring death or life; those who love to talk will reap the consequences”.
My wife and I have made an exercise of speaking the truth of God to ourselves as well as to our circumstances. If either one of us says, “this place is so nice, but so expensive” we correct ourselves by saying that we are richly blessed, money comes to us through the blessings of God, and we can afford whatever we want, etc…. Just to refute the lies of the enemy. We do the same thing in regards to health, so that whenever a symptom comes up we rebuke it from the word go.
Our faith has to work in all areas of our life. You can say that you trust God in regards to finances, but you don’t in regards to health. What you’re basically saying is that you only believe in God part way, only about certain aspects of life and not all His promises are true. So we must not only speak the Word of God about ourselves but also about who He is and about all He can do for us.
That’s why confessions of Faith are very important. We compiled quite a few from the generals of faith of our time, and you can read them here. W. E. Kenyon has an AWESOME book on professions of faith called “Power of Positive Confessions”.