There is one seemingly negative consequence of having fellowship with God and our fellow believers: we can no longer have the same sort of fellowship with unbelievers.
Do not be bound together with unbelievers; for what partnership have righteousness and lawlessness, or what fellowship has light with darkness? Or what harmony has Christ with Belial, or what has a believer in common with an unbeliever? Or what agreement has the temple of God with idols? For we are the temple of the living God. (2 Corinthians 6:14–16 nasb)
The separation from unbelievers that Paul was speaking about is not primarily physical. We may find ourselves side-by-side with unbelievers every day—in our homes, in our workplaces, or in other activities of daily life. In such situations, our Christian testimony requires us to be friendly, courteous, and helpful. But we are not free to share with unbelievers that which is morally or spiritually impure or dishonoring to Christ. In this realm, we must follow Paul’s exhortation in 2 Corinthians 6:17: “Do not touch what is unclean.” If we are sensitive to the Holy Spirit, He will always warn us of these defiling contacts and show us how to protect ourselves from them.
However, the surest protection against wrong fellowship is right fellowship. As God’s children, we are heirs to innumerable joys and blessings of which the world knows nothing. In fact, Paul told us that our Father God “has blessed us with every spiritual blessing in the heavenly places in Christ” (Ephesians 1:3). As we regularly share these blessings with the rest of God’s family, we are no longer attracted by the tawdry, impure pleasures of a world that is walking in darkness.