Iron sharpens Iron

If I am a friend of God, & He calls me friend. Then should I not represent God
In a way that draws all men to the Him?
The phrase "a man is known by the company he keeps" If your friends steal
and you associate with them regular what are the chances that sooner or later you will steal.
Or participate in their ill gotten gain?
"Know ye not that the friendship of the world is enmity with God?
whosoever therefore will be a friend of the world is the enemy of
God." (James 4:4) 
Friends Shape Friends: "Iron sharpeneth iron; so a man sharpeneth the
countenance of his friend" (Proverbs 27:17). In our text above, James
notes that the world's friendship so contrasts with the heart and mind
of God that such a friendship turns our relationship with God into
enmity. The apostle John gives the clear reason: "For all that is in
the world, the lust of the flesh, and the lust of the eyes, and the
pride of life, is not of the Father, but is of the world" (1 John
2:16).

Friends Love Each Other: "Ye are my friends, if ye do whatsoever I
command you…. I have called you friends; for all things that I have
heard of my Father I have made known unto you…. These things I command
you, that ye love one another" (John 15:14-17). This is pretty simple.
If I love the Lord Jesus, and you love the Lord Jesus, then we will
love each other—because we have a common friend!

Friends Stick Together: Because of our common love for the Lord Jesus,
we do not forsake "the assembling of ourselves together" (Hebrews
10:25). Neither do we follow the "counsel of the ungodly," or hang
around "in the way of sinners," or feel at home with "the scornful"
(Psalm 1:1), because there is no fellowship in "righteousness with
unrighteousness" (2 Corinthians 6:14).

Godly people will have godly friends. Am I telling you not to associate with co-workers
or your neighbors who are not saved Nay, I encourage you to spend time with them
and let the light of Christ shine through you that they might come to know Christ through you.
But do not share in their sin, for you know what is right in the eyes of the Lord.  Christ
 ate at Matthews house with sins but didn't participate in the sin.  If you are able to share
the gospel and the truth with them without becoming apart of their sinful practices then
yes then befriend them. But do not forsake the fellowship of the brethren for in the brethren
there is strength and encouragement.