Judges 2:1-3 The angel of the LORD went up from Gilgal to Bokim and said, "I brought you up out of Egypt and led you into the land that I swore to give to your forefathers. I said, 'I will never break my covenant with you, 2 and you shall not make a covenant with the people of this land, but you shall break down their altars.' Yet you have disobeyed me. Why have you done this? 3 Now therefore I tell you that I will not drive them out before you; they will be thorns in your sides and their gods will be a snare to you."
The command of the Lord was simple: the Israelites were not to come into any agreement, or form any connection at all, with the people of the lands they were conquering. The only one they were to make a covenant with was the Lord. Why? Because God knew that the moment they entertained any binding connection or relationship with these nations Israel would easily be enticed to follow their ways. The only way of life that the Israelites were to be influenced with was the life of God given to them in the law.
A similar command is given to Christians today.
2 Corinthians 6:14-18 Do not be yoked together with unbelievers. For what do righteousness and wickedness have in common? Or what fellowship can light have with darkness? 15 What harmony is there between Christ and Belial ? What does a believer have in common with an unbeliever? 16 What agreement is there between the temple of God and idols? For we are the temple of the living God. As God has said: "I will live with them and walk among them, and I will be their God, and they will be my people." 17 "Therefore come out from them and be separate, says the Lord. Touch no unclean thing, and I will receive you." 18 "I will be a Father to you, and you will be my sons and daughters, says the Lord Almighty."
A Christian is not to have a binding relationship with unbelievers, with those who do not believe in our Lord and walk according to His ways. Yes, we have acquaintances, friends and even family who are not believers. We cannot avoid that. But a Christian is to make sure that he is not to make any covenant or be in a league together with unbelievers, for eventually it will lead us to compromise our walk with God. It is the binding relationships (like business partnerships, marriages, fraternities, and the like) that a Christian cannot get himself out of that are dangerous for him.
But sadly, for the sake of profit, for the sake of love, and for many other reasons, Christians place themselves in relationships that threaten their walk with God. The lure of success, profit and comfort overcome the desire to please God. And we all know how strong the pull of these things are.
This is why a Christian must exert all effort to keep away from these things, to yoke himself/herself only with people who walk the same walk, talk the same talk, as genuine believers in Christ.
The Lord warned the Israelites about the consequences of their making a covenant with other nations:
3 Now therefore I tell you that I will not drive them out before you; they will be thorns in your sides and their gods will be a snare to you.
For so many years the Lord had protected and guided His people to the promised land. But if they willingly covenanted themselves with other nations, God was going to just let them be. The nations would be thorns in their sides, and their gods and other evil practices would be a snare to them, causing them to be caught in their evil ways.
Some of us who have yoked ourselves with unbelievers have experienced this. How many Christian businessmen who have partnered with non-Christians are now caught in compromising lifestyles, and are gaining profit by lying, cheating and fooling the government. How many Christians have “fallen in love” with unbelievers and have placed their partners above the Lord, and have fallen into a life of prayerlessness, immorality, and even completely turning away from the Lord.
Is this the life we want to live – a life of thorns and snares all around us? When we willingly choose the ways of this world by allowing ourselves to be partners with unbelievers God, in His grace and love, will allow that partnership to bring its consequences upon us, if only it may lead us back to a life fully surrendered, partnered and in league only with Him.
2 Cor 7:1 Since we have these promises, dear friends, let us purify ourselves from everything that contaminates body and spirit, perfecting holiness out of reverence for God.