As the crisis in Egypt develops, it is becoming increasingly clear what it is not about. It is not about the proposed constitution, many of whose provisions opposition members put their signatures to, before changing their minds and walking out of the drafting committee. Negotiations on the contentious clauses have been offered and rejected. Nor is it about the date of the referendum, which the Egyptian justice minister, Ahmed Mekki, offered to postpone. Again, this was rejected. Nor even is it about the temporary but absolute powers that the Egyptian president, Mohamed Morsi, assumed for himself – which will lapse the moment the referendum is held whatever the result.

Urging the opposition to shun dialogue, Mohamed ElBaradei said that Morsi had lost his legitimacy. So the target of the opposition National Salvation Front is not the constitution, or the emergency decree, but Morsi himself. What follows is a power battle in which the aim is to unseat a democratically elected president, and to prevent a referendum and fresh parliamentary elections being held, both of which Islamists stand a good chance of winning. Morsi, for his part, is determined that both polls be held as soon as possible to reaffirm the popular mandate which he still thinks he has.

In weighing who occupies the moral high ground, let us start with what happened on Wednesday night. That is when the crisis, sparked by Morsi's decree when he was at the height of his domestic popularity over the role he played in stopping the Israeli assault on Gaza, turned violent. The Muslim Brotherhood's Freedom and Justice party sanctioned a violent assault on a peaceful encampment of opposition supporters outside the presidential palace. But lethal force came later, and Islamists were its principal victims. Five of the six people killed in Cairo were members of the Brotherhood and one came from the opposition. Two more Islamists were killed outside the capital. Brotherhood offices were attacked up and down the country, while no other party offices were touched. This does not fit the opposition's narrative to be the victims of Islamist violence. Both sides are victims of violence and the real perpetrators are their common enemy.

Morsi undoubtedly made grave mistakes. In pre-empting a decision by the constitutional court to derail his constitution, his decree was cast too wide. The final draft of the constitution has many faults, although none are set in stone. The opposition on the other hand has never accepted the results of freely held elections, parliamentary or presidential, and is doing everything to stop new ones being held.

• This article was amended on 10 December 2012 to correct a homophone.