I am no fan of the Muslim Brotherhood or President Mohamed Morsi. He is hopelessly incompetent politically, a complete disaster economically (not that he was exactly dealt a strong hand), and acts like he is an Islamic Pharaoh. His tenure has been so bad that he's even seemingly admitted as much in a recent interview. What's worse is that over the past year he's scorned the judiciary, embarrassed the army, and has sewn deeper sectarian divisions by recently attending a rally where he castigated Shias and also by appointing a former member of the militant gang that murdered 62 tourists in Luxor in 1997 as the governor of that region.
All of that being said, you can't be a democrat and support a military coup. All of the liberals who led the original revolution and ouster of Mubarak and all of whom are now calling for the army to intervene are wrong, not to mention wholly hypocritical.
Democracy just doesn't work that way. If you want the rule by the people, then you have to live by the rule of the people regardless if you like it or not.
This is not to say that the secular youth and liberals who started the revolution aren't without grievance. While the Brotherhood cowered on the sidelines, it was the youth and liberals who risked their lives to stand up to Mubarak. They were the ones who led the movement. They were the ones who bravely occupied Tahrir Square. And they were the ones who suffered when the Brotherhood hijacked the revolution months later.
But calling the army back in to take back power in a military coup isn't smart. Replacing Morsi might be a moral boost and uplifting victory in the immediate term, but it sets a bad precedent and leads to a dangerous future.
For one, military coups are a mark of a tragic third-world country and chronic instability. Egypt is better than that and must rise above. Even if the army brings about immediate law and order (highly doubtful given the toxic and explosive political climate), being tainted and branded as such a country does lasting damage to their credibility abroad.
More worrisome though for liberals should be that the Brotherhood still has wide popular support, which it proved by sweeping to power in elections last year. If Morsi is removed from power unjustly, the Brotherhood will not go quietly. Egypt will continue to be racked by more violence, perhaps even deeper civil unrest. In the long run, no president will be ever recognized as legitimate. Islamists, the Brotherhood, and others will use the same protests we are seeing now to oust future leaders. Continued protests will only further crater the economy and damage Egypt's international standing.
Anti-Morsi protesters should back down, reorganize that he was legitimately elected, and prepare for future elections. Democracy can be unfair, but if it's democracy that the protesters truly want, then they must prove their strength at the voting booths. Morsi might be a calamitous leader, but he must be allowed to finish his term in office.