A brother in Christ asked me to do a short piece on the unequal yoking of a believer. This subject is a lot deeper than I present it here but I hope that the context helps you in understanding the implications. God bless you all as you read.
It is human nature to be drawn to like-minded people or those who think like we do and who agree with us. I can’t remember any time that I ever drew close to somebody who disagreed with me frequently, was contentious, and always did things the opposite way that I did. When someone agrees with us, it gives us and our viewpoint validation. Validation draws us closer to that person relationally, emotionally, and spiritually. Some might define this as a kindred spirit, or oneness with each other.
Given these things, we might then define living in oneness as singleness of spirit, mind, feelings, and of purpose. It is unity, sameness, thinking alike…as one, or having a single identity. . .as in marriage . For example, God gave Adam AND Eve equal dominion in the Garden of Eden. This was a singleness of purpose. When God created them in His image, this gave them unity of spirit, singleness of mind, and perfection in every way with not only each other but with a union and communion with God, meaning fellowship with both. The Bible calls this a threefold cord . Otherwise, how can we agree and live amicably and in harmony with each other, as equals. More so, how can we be in harmony with God?
v3 Can two walk together, except they be agreed? [Amos 3:3 KJV]
God is diametrically opposed and in conflict with the world’s way of thinking . How can we walk together or with God if we do not agree? If man and woman are to live together in harmony, they have to be on the same page or there will be problems. That is, unless one acquiesces to the other. When that happens they are no longer equal and do not have equal dominion that God gave them in the Garden of Eden through inheritance. The saved partner can and most likely will, drift away from God if he or she is the one who acquiesces. A relationship cannot survive with two world views. They will love the one and hate the other.
v24 No one can serve two masters. Either you will hate the one and love the other, or you will be devoted to the one and despise the other. You cannot serve both God and money. [Matthew 6:24 NIV]
Jamieson-Fausset-Brown Bible Commentary says in part about Matthew 6:24: . . .or their interests are quite different, and even conflicting. In this case, if our affections be in the service of the one—if we “love the one”—we must of necessity “hate the other”; if we determine resolutely to “hold to the one,” we must at the same time disregard, and (if he insist on his claims upon us) even “despise the other.”
If a believer is the one who acquiesces, and goes the way of the unbeliever then he or she has said in her spirit, “I choose to go the way of the world and will do what Satan tells me.
The Bible commands us (Christians), “Do not be yoked together with unbelievers. For what do righteousness and wickedness have in common? Or what fellowship can light have with darkness ?” There is not much to misunderstand there. We cannot dispute or argue against this.
The context of this 2 Corinthians Scripture is, do not hook yourself together with unbelievers. Because what harmony has Christ with Belial , or what has a believer in common with an unbeliever? Believers have the indwelling Spirit of God and if a believer unequally yokes, then how can the Spirit of God fellowship with you? For a Christian to unequally yoke to an unbeliever WILL separate you from God. He will never leave or forsake you but there will be no fellowship or blessing.
Therefore, as Amos points out, if we want to walk in agreement with the Lord daily, remain under the blessings of God, and do not want to lose fellowship with Him, then it would behoove us to follow His precepts and obey them. It is all for our benefit anyway.
John Gills Commentary on the Entire Bible says it best (in part of Amos 3:3): . . .The design of these words is to show, that without friendship there is no fellowship, and without concord no communion; as this is the case between man and man, so between God and man; and that Israel could not expect that God should walk with them, and show himself friendly to them, and continue his favours with them, when they walked contrary to him.
In other words, When we are contrary to the Lord (disobey Him), how then can we expect God to show us favor, bless us, and to fellowship with us? How can we expect to be in communion with God when there is no agreement or harmony? Hence, we drift away from God. John Gill says further; “And to a spiritual walk with God, and communion with him, agreement is requisite. God and man were originally chief friends, but sin set them at variance; a reconciliation became necessary to their walking together again. . .”
In other words, “Repent!” Repent means to turn from your wicked ways, or go in the opposite direction, with righteousness and fellowship with God as the goal. A holy and righteous path is always the goal for a Christian, otherwise, why be one?
However, have no fear, God is always there to catch us when we fall and to pick us up when we do . Trust in the LORD with all thine heart; and lean not unto thine own understanding. In all thy ways acknowledge him, and he shall direct thy paths .
Romans 6:1, 2
1 Timothy 2:14
 Genesis 2:24. When we are married, we become one (one flesh).
 Ecclesiastes 4:12
 Satan and his minions
 2 Corinthians 6:14 NIV
 Belial in this context refers to Satan because the Bible uses it here as a noun.
 Psalm 37:24; Psalms 145:14
 Proverbs 3:5-6