In this world, there is a natural tendency to separate people into groups. This could be by race, gender, age, education, athleticism or physical capability as a whole, or religion (down to different sects of religion such as denominations of Christianity. This is completely natural and okay in order to help different groups identify with experiences and events that are unique to their own makeup. For example, I could not identify with the experience of the black community because I am not black; but others that are can and do. Likewise, a man could not identify with the experience of women in society; but I can because I am a woman. So on and so forth it goes. There is nothing inherently wrong with identities, but as a society, and as Christians, when we separate others so much, we can go from creating potential for understanding and healing to division and tension, which we have seen reach breaking points in racial tensions in the US as well as globally; through the Me Too movements; and the fights between Christian groups due to minor differences in translation of the Bible (who else remembers the fight between Christians who dance and Christians who don't?).
When we start to box people in according to race, creed, class, or even different sects of the same religion, we begin to highlight the ways in which we, ourselves, are creating separations within society. Although these differences might be rooted in reality, we use them as an opportunity to quibble and lay aside other opinions, voices, and worth; instead, looking only to the surface of an individual or group, rather than toward humanities common potential of salvation. As Christians, this can be a slippery slope, because we are called to emphasize the unity of Christianity; and really, if we look down deep beneath the small stuff, there are a number of things that unite us as Children of God.
The first would definitely be the understanding that foundational aspects of Christianity are global. Salvation is global. The entire Bible itself is printed in 698 languages and the New Testament has been translated into an additional 1,548 languages. No matter where you are in the world, the Bible will always hold the same foundational truths and as Christians we all believe such truths.
Another aspect of our united Christian experience regardless of the boxes we confine ourselves to, is Communion. We all sin, even as children we are prone to sin and tied to the original sin in the Garden, so we need Communion; and Jesus knew this so He taught us how to share in Communion in the same way as one another. We need to recognize this as the need for atonement of all souls and especially when teaching our young ones about Communion and how it brings us all together. In this, we can also understand that however good we are, none of us is perfect and we need Communion to recognize this and to come into fellowship with the perfect one.
We also, as humans, have another connection which transcends labels or groups and that's our ability to communicate with one another and the intellectual capability to understand speech. The reason why this is so important is that this ability isn't limited to the own languages we know currently. We can learn other languages and can communicate virtually limitlessly with one another and we can and should be using this, not to divide one another, but to profess how God sees others and how He counts them as worthy and equal in Christ. In Galatians 3:28, it says, "There is no longer Jew or Gentile, slave or free, male and female. For you are all one in Christ Jesus." This is a beautiful reminder from the Apostle Paul that while there may be actual differences between us and our experiences on this earth, it is faith that holds us together and what should define us above all else.