Amos 3:3

So here the Lord warns His people through the prophet. He had explained to them the moral principle; now He lets them know His ways in certain brief parables or comparisons. … First, what fellowship could there be between God and His people in the state they were in? Next follow signs of the sorrow in store for them. The lion's roar for his prey, the snare for the bird and the loud blast of warning for the careless people all point to it.

If we are in the place of testimony — of testimony to God — this testimony needs to agree with the heart and the principles of God. It must not misrepresent His character. Our walk should agree with our position. And the more direct this testimony is, the more jealous God will be about His glory and our faithfulness. Judgment begins at His house… Two cannot walk together unless they are agreed.

Fellowship is only possible on the ground of separation; a holy God demands a holy people. In their state of immoral idolatry and blatant injustice the Lord could not own them.

It is evil association that constantly corrupts the manners of the Lord's people. Mixture is Satan's constant device, and compromise necessarily grows out of mixture. We cannot walk together unless we are agreed. People may say, and do say, "We agree this far; why can we not walk together at least in what we already share?" All right, if Christ and His will and Word are not left out of the agreement; but when the Church joins with the world, this must of necessity be left out.

Men refuse to draw the conclusion, but that in no way stops the just judgment of God in the matter. The consequences of our acts will follow as surely as if we swallowed poison believing it was good food. Many have found the disastrous effects of alliances — social, commercial or religious. They made them under the soothing illusion that the alliances were fine, because only Christians were involved.

Two cannot walk together, or sail together, or work together, or worship together, "unless they are agreed." And if you say that on such terms there can be no fellowship at all, it only proves one thing. You have never resolved at any cost to find the truth and, having found it, to put it into practice.

We may question the action of the two who went "to a village called Emmaus" (Luke 24), but they at least were "agreed" as they walked… "Slow of heart" and unbelieving — yes, indeed… but they were speaking together of Him… Suppose our minds and affections were firmly fixed on our Lord, and on the glories of His person that He has shown us. Then we would speak less of the failures and divisions among His people, except in secret prayer and confession. And we would speak more of Himself and His interests.

Though Abram could not live with Lot, he still runs to his help when Lot is in distress. Fellowship of saints is one thing; helping a brother in need is another. Helping is always binding (1 John 3:17). Fellowship is not always possible, for how can two walk together unless they are agreed?