Grace is not going to lead us to speak poorly, badly, or negatively about anything, anyone, at anytime. (Eph 4:29) "Let no corrupt word proceed out of your mouth, but what is good for necessary edification, that it may impart grace to the hearers."
Actually our words reflect what is in our heart and what we are believing at the time: (Lu 6:45) "A good man out of the good treasure of his heart brings forth good; and an evil man out of the evil treasure of his heart brings forth evil. For out of the abundance of the heart his mouth speaks." (Note: For us as born again believers the "good man" is our born again spirit and the "evil man" is our old sin nature.)
Pay attention to our mouth! It is amazing the amount of things we say that go unnoticed by our brain. We often criticize others for saying one thing and doing another while we don't notice we do it to. We can actually speak life and death from the same mouth in very close proximity. James puts it this way: (Jas 3:10) "Out of the same mouth proceed blessing and cursing. My brethren, these things ought not to be so." We can locate our heart by what questions we ask or by the statements we make (See booklet "Indicators and Location" at our website Lordsbcc.org/booklets).
Why does our mouth have so much power?