Scripture plainly reveals that God repeatedly calls for His people to separate from the world. This separation extends to every aspect of life, especially including the marriage bond. Why? Because God knows the very real danger that unbelievers pose to believers by drawing them away from Him (Deuteronomy 7:3-4; Judges 3:6-7; 1 Kings 11:2). This is why God specifically instructed His people in both the Old and New Testament to marry among themselves (Jew with Jew and Christian with Christian). The nation of Israel was forbidden to yoke up with the surrounding nations because Israel would adopt heathen practices and the worship of false gods (Exodus 34:15-16). Though God’s commands for the New Testament believer are often different from His plan for the Jew, in this aspect they remain constant and unchangeable.
Imagine the vulnerabilities of a watchman who refuses to keep his eyes open to every possible angle from which danger could arise. No doubt the enemy would scout the land observing the bad habits of the watchman. If the watchman fails to examine each point of entry, the enemy will attack from the unprotected angle. In like manner, believers are to walk circumspectly. The word circumspect means to look all around. Believers are to be sober and vigilant knowing that their enemy, the Devil, “walketh about, seeking whom he may devour” (1 Peter 5:8). God’s enemies always search for the weak spot where the hedge has been cut down or ignored. This is why there is no angle in the believer’s life that can be safely ignored.