Our Scripture reading today is Ezekiel 33:7-9.
Verse 7, "So thou, O son of man, I have set thee a watchman unto the house of Israel; therefore thou shalt hear the word at my mouth, and warn them from me."
The prophet Ezekiel heard directly from God that judgement was coming and he was compelled to announce it.  God has called all of His children in every generation to be watchmen.  A watchmen is someone who gives a warning about the enemy.  In order to do this effectively, we are to learn truth from the Word of God and then communicate that truth to those who are not a part of the family of God.  
It is true that we do not have the power to win people to Jesus Christ, but we are definitely commanded to warn them regarding the penalty for their sin.  Romans 6:23, "For the wages of sin is death..."  We are to lovingly warn them of the coming judgement of God.  Ephesians 4:15, "But speaking the truth in love, may grow up into him in all things, which is the head, even Christ:  
There is no better day than today to sound the alarm to those we know and love.  Life on this earth is a vapour, but the soul of man will live forever in Heaven or Hell.