"And, behold, the glory of the God of Israel came from the way of the east and His voice was like a noise of many waters: and the earth shined with His glory." (Ezekiel 43:2)
Without a doubt, God speaks through the sea of humanity in which we find ourselves. "The madness of crowds" isn't entirely inaccurate. Look at what Solomon says in Proverbs (18:4): "The words of a man's mouth are as deep waters, and the wellspring of wisdom as a flowing brook."
Just because you don't know—or even like for that matter—the person speaking to you doesn't mean you shouldn't listen. It doesn't mean that a supervisor, someone standing in line, or even anyone else who might be a complete stranger isn't the person the Lord is using to speak to you. Jesus makes an incredibly poignant and pointed statement when He says "the children of this world are, in their generation, wiser than the children of light" (Luke 16:8). What does this mean? It means we can learn from everyone. He continues on in the next verse saying, "make unto yourselves friends of the mammon of unrighteousness". I know He's talking about dealing wisely with finances and creditors, etc. But look at it from another, broader angle. Paul says (in Romans 12:18) "If it be possible, as much as lieth in you, live peaceably with all men (and women)." This is what Jesus did. He ate with and was friends with "publicans and sinners" (Matthew 11:19). And He won the heart of anyone who was humble and genuine. As we pass through "the paths of the sea" (Psalm 8:8), we need to do as Paul taught in Romans. Live at peace with our neighbors. He says if we do, they'll see God. God gives us the privilege and honor of revealing Jesus to the world through our way of life.
The Bible is replete with stories of God using those who didn't know Him (yet) to bless those who He had chosen to do on earth what needed to be done. Isaiah 45 is God speaking to King Cyrus of Persia. God says in verse four (emphasis mine): "For Jacob my servant's sake...I have even called thee by thy name...though thou hast not known me." God is not limited in how He'll reach us. It's we who become dull to His voice, thinking that He has to use our pastor only, or anyone else we deem and deign worthy.
"For there is no respect of persons with God." (Romans 2:11)
Going back to the sea of humanity. Job says (28:10) that God's eye "seeth every precious thing." People are precious. Anyone who has a gift—of wisdom, insight, experience, point of view, etc.—should be willing to use it to benefit those who need it. And if we live in humility and selflessness, being willing to learn from anyone God chooses, He will bless and teach us through our neighbors. And everyone's our neighbor whether they know Jesus or not. This opens up a wonderful opportunity to show the love of God to everyone we meet. Maybe we'll even get to bring them along with us on our way through the "deep places of the earth" (Psalm 95:4)?