Yes, unfortunately it is characteristic of humans. And Christians are human first. God has forgiven them, and now, by an act of my will, in spite of my feelings, I choose to forgive them also. Unfortunately, because of our misguided albeit genuine beliefs about God and erroneous expectations of the Christian life, and because of unresolved hurts in our lives and living in a sinful world, the cycle of contempt and criticism continues. Sibling rivalry stands strong.
Fragile faith is broken.
The cause of Christ is contaminated. The good news is that with knowledge there is understanding and with understanding, change. But the best news is that no matter what we have suffered at the hands of others, no matter what pain persists from our past or prevails in our present, Christ is there for us. His greatest desire is to be the One we run to for comfort and strength. To bear our burdens and heal our wounds.