How should Christians act toward non-Christians?

Question

How should Christians act toward non-Christians?

One example I have found is 2 Corinthians 6:14 [KJV].

Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?

I believe this is saying not to marry non-Christians.

Are there any other instructions on how to behave towards non-Christians in the Bible?

Answer 1

They are our neighbors and we should love them as ourselves.

John 13:34-35 (NIV)

   ³⁴ “A new command I give you: Love one another. As I have loved you, so you must love one another. ³⁵ By this everyone will know that you are my disciples, if you love one another.”

If it turns out that they are our enemies then we should love them all them more.

Matthew 5:43-44 (NIV)
    ⁴³ “You have heard that it was said, ‘Love your neighbor and hate your enemy.’ ⁴⁴ But I tell you, love your enemies and pray for those who persecute you,

Answer 2

You're right, from a strictly Biblical perspective, marriage to non-Christians should be off the table. Personally, I've even witnessed relationships between denominations deteriorate due to theological differences, but in an inter-religion marriage there can be some serious issues -- either faith is watered down, or it is a source of contention.

We are also cautioned not to give that which is holy to those who are not baptized:

Give not that which is holy to dogs; neither cast ye your pearls before swine, lest perhaps they trample them under their feet, and turning upon you, they tear you. (Mat. 7:6)

The ancient Church (the Catholics only ended this recently and my understanding is that the Orthodox continue to do this to today) took this to mean that the outsider was welcome through the preaching and recitation and exposition on the religious texts, but that the holy meal was reserved to the initiated (read up on mystagogy for good stuff on this)

Some can be read into the admonitions related to what later became excommunication. Here is a pertinent text about those who have fallen into habitual (in this case sexual) immorality:

To deliver such a one to Satan for the destruction of the flesh, that the spirit may be saved in the day of our Lord Jesus Christ.(1 Cor. 5:13)

And, according to the Johannine texts these should not be considered part of the congregation:

Whosoever revolteth and continueth not in the doctrine of Christ hath not God. (2 John 9)

That said the story of the Good Samaritan would suggest that love crosses all bounds (and if you want a fascinating history, read about Israel, Judah, and the origin of the Samaritans). Further, the Old Testament is full of admonitions to defend the foreigners:

If a stranger dwell in your land, and abide among you, do not upbraid hin: But let him be among you as one of the same country. And you shall love him as yourselves: for you were strangers in the land of Egypt. I am the Lord your God. (Lev. 19:33-34)

It seems, all considered, that the admonition to love (cf. Mt. 7:12, Lk. 6:31) is universal and should be universally applied, but the alien is still an alien. It is fine to fellowship with those in the world, but spiritual communion should be reserved to those who are among the flock.

Answer 3

The way Jesus treated each and every one of the people he encountered; with love, compassion and mercy.

• Love your neighbor as yourself. (See Mark 22:39)
• Love your enemies, and pray for those who persecute you. (See Matthew 5:44)
• Do unto others as you would have them do unto you. ("Golden Rule")

It's all there in the Gospels and Paul's letters to the churches, Jesus is who we should aim to emulate.

Answer 4

In addition to the [obvious] exclusion of marriage, it would seem to indicate (in my understanding) that we should not become unduly-bound to an unbeliever in other relationships, as well.

It is [likely] impossible for one to only work with and for another christian. However, intentionally going into business with an unbeliever could be considered an unequal yoking.