He shall cover thee with his feathers, and under his wings shalt thou trust: his truth shall be thy shield and buckler. Psalms 91:4 KJV
As we speak God’s truth, we are covered by His truth. Our words are spirit just as Jesus said in John 6:63, It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life.
Proverbs 8:6-9 (KJV)
6 Hear; for I will speak of excellent things; and the opening of my lips shall be right things.
7 For my mouth shall speak truth; and wickedness is an abomination to my lips.
8 All the words of my mouth are in righteousness; there is nothing froward or perverse in them.
9 They are all plain to him that understandeth, and right to them that find knowledge.