According to Quran and traditions, the Muslims who fought the Hujjah (Imam) of the era are worse than disbelievers.
Imam Muhammad Baqir (a.s.) while discussing those who fought Ali (a.s.) – Know that they are greater criminals than those who fought the Holy Prophet (s.a.w.a.).
He (a.s.) was asked – How is that O Son of Allah’s Prophet?
He (a.s.) informed – They were the people from the era of ignorance (Jahiliyyah) while these ones recited the Quran and they recognized the people of merit then they did what they did despite the knowledge.
- Mustadrak al-Wasail v 11 p 62, 66v
- Manaqib Aal Abi Talib (a.s.) v 3 p 218
- Behaar al-Anwaar v 32 p 322
Likewise those abandoned the Holy Prophet (s.a.w.a.) in the battles of Uhud, Hunain, etc were worse than infidels who fought the Holy Prophet (s.a.w.a.) in these battles as this incident highlights:
The second ruler informs:
On the day of Uhud, the Holy Prophet (s.a.w.a.) took the pledge that none of us would flee the battle and one who does so, would be deviated and the one killed would be a martyr.
When we fled from the battle – Ali (a.s.) came after us saying – You have broken the pledge to the Prophet (s.a.w.a.) and are more deserving to be killed than these (infidels) I have killed.
- Behar al-Anwar v 20 p 53
While religion at the time of Holy Prophet (s.a.w.a.) and Ameerul Momineen (a.s.) faced danger from external threats, the hypocrites and traitors within the fold posed the greatest danger. More was expected from them since they had pledged to support religion at all cost. By reneging on their pledge, they turned out to be worse than infidels.