Do not be bound together with unbelievers; for what partnership have righteousness and lawlessness, or what fellowship has light with darkness?2 Corinthians 6:14(NASB)
Paul had to admonish Christians in various churches for their ungodly ways and from distancing themselves from the important issues of Christian conduct, which are necessary for godly living and effective ministry. In the Corinthian church, it was a lack of love and a cooling of affection towards Paul himself that he identified. Indeed, he was quick to point out that the main reason for their lack of warmth towards him was because of their close, 'chummy' and incongruous association with unbelievers.
Paul recognised that the divided loyalties of these believers was negatively impacting their close Christian communion, causing a serious spiritual disconnection between them. And so Paul warned of the dangers this behaviour had on their spiritual growth. And this is the inevitable outcome for any believer who gets bound-up in close, un-sanctified, worldly friendships, or becomes emotionally enmeshed with inappropriate alliances.
"Do not be bound together with unbelievers;" was Paul's warning, "for what partnership is there between righteousness and lawlessness, or what fellowship has light with darkness?" James also reminds us that friendship with the world is hostility toward God, while John entreats us not to love the world nor the things in the world.
Paul gave a strong warning against choosing to become unequally yoked together with unbelievers. He counselled against choosing to get bound up together with non-Christians or becoming intimately associated with those who are not saved. Paul knew that the inevitable outcome is an increasing disassociation from the Lord, a distancing of oneself from Christian brethren, and even a quenching of the Holy Spirit in their lives - all of which inhibit spiritual development and result in a backslidden life.
The general principle is that any relationship that hinders or prohibits a developing relationship to the Lord is better terminated - even before it begins to develop. Paul was not implying that the Christian must be completely isolated from unbelievers, nor was he condemning casual interactions, involvement in a working relationship, or even social contact - but the general principle that Paul was teaching is that Christians should never initiate, maintain, or desire close, intimate association with unbelievers, as this inevitably prevents or inhibits close communing with the Lord, has a serious impact on spiritual growth, adversely affects relationships with other believers, and grieves the Spirit of God.
Like many of Paul's instructions, this is not a law that is to be strictly imposed on believers but a general principle that each of us needs to apply to our own life - or to be given as wise, biblical counsel to those who may have become embroiled in an unwise alliance. He is encouraging wise personal judgment when choosing and maintaining special relationships in our lives, and certainly not imposing any legalistic command that must be followed rigidly. But we all need to look at our own lives... and reflect on the friendship choices that we have made or are considering, and to base our choice on wisdom from the Word of God and the godly counsel of spiritual Christians.
Heavenly Father, thank You that I am Your child and have been made a new creation in Christ. Help me to choose my friends and acquaintances wisely. Direct me, I pray, in the choices I make with regard to the close, personal relationships that I choose to engage in, and may all I say and do be to Your praise and glory. In Jesus' name, AMEN.