God told us to evangelize our family and friends but He never said we should remain as close friends. Here are some principles from the Word that warn us about keeping close friends who do not love the Lord.
Amos 3:3 "3 Can two walk together, except they be agreed?"
The answer is no because we become like those who are our close friends.
1 Corinthians 15:33-34 "at did I gain? If the dead are not raised, “Let us eat and drink, for tomorrow we die.” 33 Do not be deceived: “Bad company corrupts good character.” 34 Sober up as you ought, and stop sinning; for some of you are ignorant of God. I say this to your shame.…"
The problem I see often is the excuse to be friends with unbelievers to evangelize them is not completely honest. The truth is that if we speak of God frequently in our walk the unbeliever will become weary of hearing it and go away. I suggest that to maintain friends with an unbeliever we must remain silent about God.
How can we not speak frequently about our Lord Whom we love above everyone and everything else in the world?
What good is our testimony if we never speak of Christ. It only makes the unbeliever comfortable in their own sinful life. "Lifestyle evangelism" is a lie. That being just living for Christ is enough without saying anything.
Romans 10:14 "How then will they call on Him in whom they have not believed? How will they believe in Him whom they have not heard? And how will they hear without a preacher?"
We are not called to be "friends" with unbelievers, we are called to speak the truth of Christ to them, if they do not listen we are to remove ourselves. We can always be available if they want to come and find out more. They know where we live and what we believe.
Matthew 10:14 "Whoever does not receive you, nor heed your words, as you go out of that house or that city, shake the dust off your feet."
James 4:4 "You adulteresses, do you not know that friendship with the world is hostility toward God? Therefore whoever wishes to be a friend of the world makes himself an enemy of God."
Our modern Christianity claims that if we just hang around non-believers a lot eventually they will want to hear. This could not be farther from the truth.
I believe there are many people using the excuse about evangelizing their unsaved friends to remain friends with those who do not love God. They enjoy the company of their friend more than they love God. If they loved their friend they would evangelize them. The believer would speak of their Lord often because He is everything to them.
I hear believers all the time using filthy or crude words, its because their constant companions are unbelievers more than righteous Christ-followers. This is strong evidence that non-believers influence our ways if we have them as our constant companions. God said this was true in 1 Corinthians 15:33 "33 Do not be deceived: “Bad company corrupts good character.”