Do you not realize that God’s kindness is meant to lead you to repentance? Romans 2:4
Good parents shower kindnesses on their children and others. Kindness is a habit that is learned and the benefits of kindness are shown to you in the blessings of God each day. How can one be mean and angry while loving God who is ultimate in showing kindness to you? An unkind one is a curmudgeon.
Apostle Paul explains his thoughts on the crusty curmudgeon to actually be of any age, sex, race. There are crusty Christians who are judgemental of others yet, Paul reminds us, God is the only judge and we all fall short of being the best Christians we can be for God. A believer has a bonus with salvation: a conscience that is fine tuned to the Holy Spirit.
Listen to your conscience to chip off your crusty critical thoughts and words.