Sometimes God even uses those who aren't his followers to speak the truth. I love the following passage from Daniel 6:25-27 where King Darius says the following:
"Peace be multiplied to you. I make a decree, that in all my royal dominion people are to tremble and fear before the God of Daniel, for he is the living God, enduring forever; his kingdom shall never be destroyed, and his dominion shall be to the end. He delivers and rescues; he works signs and wonders in heaven and on earth, he who has saved Daniel from the power of the lions."
Darius speaks quite a bit of truth in this short passage: All people are to fear the God of Daniel. This God is living and endures forever. His kingdom and rule shall never end. He is the God who rescues. This God is one who works miracles.
What a glorious God we serve! Sometimes even the lost recognize this.