We are spiritually kin to all those who claim God as Father.  We belong to all of those who follow Jesus.  We are linked to them and they to us.  We are brothers and sisters in a common family.  When brothers and sisters turn on one another it breaks the heart of the Father.  To disown other Christians is to cause pain to the Lord of all Christians.  The Holy Spirit is a uniting presence in the body of believers, and to divide from one another is to grieve the Spirit.  Cherish your brothers and sisters.  It makes God happy.

“May the God who gives endurance and encouragement give you a spirit of unity among yourselves as you follow Christ Jesus, so that with one heart and mouth you may glorify the God and Father of our Lord Jesus Christ. Accept one another, then, just as Christ accepted you, in order to bring praise to God.” Romans 15:5-7 (NIV)