- Both believe in the inerrancy of the bible (Psalms 12:6, 119:89, Proverbs 30:5-6, 2 Timothy 3:16-17, 2 Peter 1:20-21, Rev 22:18-19) and in their absolute correct interpretation.
- Both believe that the other is apostate (2 Thessalonians 2:3-4).
- Both believe that the other’s doctrine is influenced by the devil (Genesis 3:1-15, John 8:44).
- Both believe the other is condemned for their false beliefs (2 Peter 2:1-3, 1 Timothy 4:1-3, 2 Timothy 2:16-19, Hebrews 6:4-8).
- Neither would darken the door of the other’s sanctuary, for fear of contamination.
- Both would avoid casual association (Proverbs 13:20, 1 Corinthians 5:11, 15:33), and certainly would not marry the other (2 Corinthians 6:14).
- Both believe that Armageddon is imminent and look forward to the purified world afterwards.
- Both consider that the highest form of charity is to convert another. Practical works like feeding the poor are considered inferior.
More? Can we make it a dozen (a more perfect number)?