Based on Philippians 4:20-23, James Montgomery Boice encourages the Christian to treat other believers, not in proportion to their present level of sanctification but to their heavenly righteousness.

Paul knew that it was these very human brothers and sisters in Christ, some of whom had been sharply critical of him, who would one day join in the great heavenly chorus to sing God’s praises.  He rejoiced that they would give God glory.  Do you think that way about the Christians you associate with?  Some of them are objectionable, and some may be extremely critical of you.  Some have experienced very little sanctification.  But God is going to use them to acknowledge his glory.  They, just like yourself, will be part of the heavenly chorus.  Perhaps it will help you to live with them (and them to live with you) if you will think of them in terms of their destiny instead of their objectionable characteristics and conduct.”

James Montgomery Boice