Is it good to have close friendships with unbelievers?

As Christians, we have to constantly face temptations and the attacks
of the world around us. Everything we see, read, do, hear, put in our
bodies, etc., affects us somehow. That's why, to maintain a close
relationship with God, we have to put aside our old ways of doing
things—the things we watch on TV, old bad habits (excessive drinking,
smoking, etc.), the activities we participate in, and the people we
spend our time with. People are divided into only two categories,
those who belong to the world and its ruler, Satan, and those who
belong to God (Acts 26:18). These two groups of people are described
in terms of opposites all through the Bible; e.g., those in
darkness/those in the light; those with eternal life/those with
eternal death; those who have peace with God/those who are at war with
Him; those who believe the truth/those who believe the lies; those on
the narrow path to salvation/those on the broad road to destruction,
and many more. Clearly, the message of Scripture is that believers are
completely different from nonbelievers, and it is from this
perspective that we must discern what kind of friendships we can
really have with unbelievers.

The book of Proverbs has a few wise verses on believers befriending
non-believers: "The righteous should choose his friends carefully, for
the way of the wicked leads them astray" (12:26). We should stay away
from foolish people (13:20, 14:7), from people who lose their temper
easily (22:24), and from the rebellious (24:21). All these things
represent those who have not been saved. "Do not be yoked together
with unbelievers. For what do righteousness and wickedness have in
common? Or what fellowship can light have with darkness?" (2
Corinthians 6:14). First Corinthians 15:33 tells us that bad company
corrupts good character. Unbelievers are slaves to sin (John 8:34),
and Christians are slaves to God (1 Corinthians 7:22). If we become
deeply involved (either by friendship or a romantic relationship) with
non-Christians, we are setting ourselves up for turmoil. It can (and
does often) cause the Christian to stumble in his walk, fall back into
a sinful life, and also turn others away from God (by misrepresenting
God and Christianity). Another detrimental effect of closeness with
unbelievers is our tendency to water down the truths of Scripture so
as to not offend them. There are difficult truths in the Word of God,
truths such as judgment and hell. When we minimize or ignore these
doctrines or try to "soft pedal" them, in essence we are calling God a
liar for the sake of those already in the grasp of Satan. This is not
evangelism.

Although these close relationships are not recommended, it does not
mean we turn our noses up and ignore unbelievers, either. Second
Timothy 2:24-26 tells us that as servants of the Lord, we are to be
kind to and not quarrel with anyone. We should gently teach those who
oppose the truth, and be patient with difficult people. Matthew 5:16
tells us, "Let your good deeds shine out for all to see, so that
everyone will praise your heavenly father." We should serve
unbelievers so that they may see God through us and turn to Him in
praise. James 5:16 says that there is great power in the prayer of a
righteous person, so bring your concerns for unbelievers before God,
and He will listen.

Many people have been saved because of the prayers and service of
Christians, so don't turn your back on unbelievers, but having any
kind of intimate relationship with an unbeliever can quickly and
easily turn into something that is a hindrance to your walk with
Christ. We are called to evangelize the lost, not be intimate with
them. There is nothing wrong with building quality friendships with
unbelievers – but the primary focus of such a relationship should be
to win them to Christ by sharing the Gospel with them and
demonstrating God's saving power in our own lives.