The tag line to Cornerstone Church is that we are "a place where faith and family grow." It's good; I like it. And yet, it is passages like Matthew 12:46-50 that tell me we need to be careful to understand "family" as Jesus understood family or we just may become an unbiblical church.
In this passage, Jesus' mother and brothers (younger siblings of Jesus born to Mary and Joseph) are trying to get into an overcrowded house where Jesus is located. When someone informs Jesus of the presence of his "mother and brothers" outside, He asks, "Who is my mother, and who are my brothers." Like you, the people in the room kept quiet because they knew Jesus wasn't going to give the answer everyone was thinking in their heads. Then he says, "Here[that is, those inside the house] is my mother and my brothers. For whoever does the will of my Father in heaven is my brother and sister and mother."
Rather than suggest applications, I would like to throw out a few implications:
1) The spiritual family takes precedent over the physical family.
2) Obedience to God supersedes obedience to family.
3) Pursuing God will often create a divide with our physical family.
4) Most people won't get it.
How this shakes down for our church or your church is important. But it's important that we wrestle with these implications and ask God to help us love each other and bear with each other, even if we have different ideas on what is the best application for our own local fellowship. In the end, remember, Jesus left His heavenly Father and the glory of heaven so that He could die alone, forsaken, on a cross for the sins of the whole world. Through this amazing act, He has reconstituted a family of brothers and sisters in Him (the church) to worship Him and serve Him. Our physical parents sacrificed for us in immeasurable ways and we need to honor them and love them. And yet, our Savior Jesus Christ gave up so much more that we might be His . . . that we might be His (1 Cor. 6:19-20)!
Blood is thicker than water, but Christ's blood is an even more powerful substance to create a family of believers of all tribes, nations, people and tongues. Hallelujah!