The concept of family is extremely important in the Bible, both in a physical sense and in a theological sense. The concept of family was introduced in the very beginning, as we see in Genesis 1:28, "God blessed them and said to them, ‘Be fruitful and increase in number; fill the earth and subdue it. Rule over the fish of the sea and the birds of the air and over every living creature that moves on the ground.'" God’s plan for creation was for men and women to marry and have children. A man and a woman would form a "one-flesh" union through marriage (Genesis 2:24), and they with their children become a family, the essential building block of human society.
We also see early on that family members were to look after and care for one another. When God asks Cain, "Where is Abel your brother?" Cain’s response is the flippant "Am I my brother’s keeper?" The implication is that, yes, Cain was expected to be Abel’s keeper and vice versa. Not only was Cain’s murder of his brother an offense against humanity in general, but it was especially egregious because it was the first recorded case of fratricide (murder of one’s sibling).
The Bible has a more communal sense of people and family than is generally held in Western cultures today, where citizens are more individualized than people in the Middle East and definitely more so than the people of the ancient near East. When God saved Noah from the flood, it wasn’t an individual case salvation, but a salvation for him, his wife, his sons and his sons’ wives. In other words, his family was saved (Genesis 6:18). When God called Abraham out of Haran, He called him and his family (Genesis 12:4-5). The sign of the Abrahamic covenant (circumcision) was to be applied to all males within one’s household, whether they were born into the family or are part of the household servant staff (Genesis 17:12-13). In other words, God’s covenant with Abraham was familial, not individual.
The importance of family can be seen in the provisions of the Mosaic covenant. For example, two of the Ten Commandments deal with maintaining the cohesiveness of the family. The fifth commandment regarding honoring parents is meant to preserve the authority of parents in family matters, and the seventh commandment prohibiting adultery protects the sanctity of marriage. From these two commandments flow all of the various other stipulations in the Mosaic Law which seek to protect marriage and the family. The health of the family was so important to God that it was codified in the national covenant of Israel.
This is not solely an Old Testament phenomenon. The New Testament makes many of the same commands and prohibitions. Jesus speaks on the sanctity of marriage and against frivolous divorce in Matthew 19. The apostle Paul talks about what Christian homes should look like when he gives the twin commands of “children, obey your parents” and “parents, don’t provoke your children” in Ephesians 6:1–4 and Colossians 3:20–21. In 1 Corinthians 7, the unbelieving spouse is “sanctified” through the believing spouse, meaning, among other things, that the unbelieving spouse is in a position to be saved through the witness of the believing spouse.
Let’s now turn our attention to the theological concept of family. During His three-year ministry, Jesus shattered some prevailing notions of what it meant to be part of a family: "While Jesus was still talking to the crowd, his mother and brothers stood outside, wanting to speak to him. Someone told him, ‘Your mother and brothers are standing outside, wanting to speak to you.’ He replied to him, ‘Who is my mother, and who are my brothers?’ Pointing to his disciples, he said, ‘Here are my mother and my brothers. For whoever does the will of my Father in heaven is my brother and sister and mother’” (Matthew 12:46-50). Now we must clear up some misconceptions with this passage. Jesus is not saying that biological family isn’t important; He is not dismissing His mother and brothers. What He is doing is making the clear theological point that in the Kingdom of Heaven, the most important family connection is spiritual, not physical. This is a truth made explicitly clear in John’s Gospel, when the evangelist says, "Yet to all who received him, to those who believed in his name, he gave the right to become children of God—children born not of natural descent, nor of human decision or a husband’s will, but born of God" (John 1:12-13).
The parallels are quite clear. When we are born physically, we’re born into a physical family, but when we are "born again," we are born into a spiritual family. To use Pauline language, we are adopted into God’s family (Romans 8:15). When we are adopted into God’s spiritual family, the Church, God becomes our Father and Jesus our Brother. This spiritual family is not bound by ethnicity, gender or social standing. As Paul says, "You are all sons of God through faith in Christ Jesus, for all of you who were baptized into Christ have clothed yourselves with Christ. There is neither Jew nor Greek, slave nor free, male nor female, for you are all one in Christ Jesus. If you belong to Christ, then you are Abraham’s seed, and heirs according to the promise" (Galatians 3:26-29).
So what does the Bible say about family? The physical family is the most important building block to human society, and as such, it should be nurtured and protected. But more important than that is the new creation that God is making in Christ, which is comprised of a spiritual family, the Church, made up of all people who call upon the Lord Jesus Christ as Savior. This is a family drawn "from every nation, tribe, people and language" (Revelation 7:9), and the defining characteristic of this spiritual family is love for one another: "A new command I give you: Love one another. As I have loved you, so you must love one another. By this all men will know that you are my disciples, if you love one another" (John 13:34-35).