I got a good question today about Mark 10:29:31. How do we make sense of Jesus' words about leaving family members when Scripture puts a emphasis on our duties to other members of our household? This is how I responded:



I think Jesus is addressing situations where one who would have to choose between Jesus and family. If a person becomes a Christian and his family cuts him off, Jesus will reward him and compensate him for his loss (and that happens at least partly in the new “family” he finds in the church).
John 9 is an example of this dynamic. The man who was born blind was cast out of the synagogue because he confessed Jesus healed him. His parents abandoned him because they feared the Jewish leaders. He is left all alone with Jesus (Psalm 27:10). He is wrongfully excommunicated and wrongfully forsaken by his mother and father -- and all for Jesus' sake. But what is the result? The man born blind loses everything, but gains new life, new sight, and a new family when he becomes a disciple.
A lot of times converts from Jewish and Muslim backgrounds experience this kind of abandonment -- to become a Christian means being cut off from family, disinherited, etc. 
Jesus addresses the same reality in Matthew 10:21-22. Our hope is always that the gospel would convert and restore whole families (“grace restores nature”). But sometimes grace rips a family apart. Jesus makes it clear that in those cases we must put loyalty to him over loyalty to family (or nation or anything else).
It’s interesting that in Mark 10 Peter says “we have left all.” In this case, I think it was temporary. The apostles did leave their families, jobs, etc. for a while to join with Jesus as he inaugurated his kingdom. But this was a pretty unique circumstance. A parallel passage would be Like 9:57-62. Normally it would be an obligation to honor your father by burying him. But at that moment, going with Jesus to Jerusalem to inaugurate the kingdom would be a higher priority. We know the apostles leaving their families was only temporary, not normative, because later we find that Peter traveled on his missionary journeys with a wife (1 Cor 9:5).