Structures, walls are built, many times subtly, quietly, over time. People notice, but the changes can be almost imperceptible. Other walls are built by the blatant sin of men, quickly, publicly. Either way, Jesus and the New Testament writers speak of unity and oneness that overcome division.  Consider their encouraging words:

A new commandment I give to you, that you love one another: just as I have loved you, you also are to love one another.  By this all people will know that you are my disciples, if you have love for one another.   – John 13:34-35  ESV

I do not ask for these only, but also for those who will believe in me through their word, that they may all be one, just as you, Father, are in me, and I in you, that they also may be in us, so that the world may believe that you have sent me.        – John 17:20-12  ESV

But now in Christ Jesus you who once were far off have been brought near by the blood of Christ.  For he himself is our peace, who has made us both one and has broken down in his flesh the dividing wall of hostility by abolishing the law of commandments expressed in ordinances, that he might create in himself one new man in place of the two, so making peace, and might reconcile us both to God in one body through the cross, thereby killing the hostility.  – Ephesians 2:13-16  ESV

There is neither Jew nor Greek, there is neither slave nor free, there is no male and female, for you are all one in Christ Jesus.  And if you are Christ’s, then you are Abraham’s offspring, heirs according to promise.     – Galatians 3:28-29  ESV