Before the Egyptian revolution began in 2011, the Muslim Brotherhood was a civil-society movement. But then the leadership had a choice: transform the movement into a political party - or not. The consequences of that decision will have repercussions for the Brotherhood's future, Egypt's political sphere and Muslim communities worldwide.
It was inevitable that Brotherhood members would enter into politics in some fashion after the January 25 revolution. But the way they have done so has created tensions within the organisation. Electoral politics means difficult choices, which a social movement can avoid. Just forming a party involved controversy. The Brotherhood leadership insisted that any member who wanted to be involved in politics must be part of the newly formed Freedom and Justice Party (FJP). Otherwise, they would be expelled.
This was a clear message: the Brotherhood was no longer a movement, it was a government-in-waiting - and would consider dissent accordingly. When the long-time member and influential reformist Abdel Moneim Aboul Fotouh decided to stand for president, he was ejected.
During the Mubarak era, there had always been different ideological trends within the Brotherhood. The FJP, however, demands adherence to one party line.
The decision to transform into a political party may come at a price. The Brotherhood was founded on religious grounds, and it has since inspired other groups in the Arab world, as well as within Muslim communities farther afield. The underlying assumption behind its popularity has been its claim on the moral high ground - which was easier when it was the underdog.
The FJP was not founded as a movement or an opposition force: it was founded to govern. In one sense, the Brothers have been successful: they have the lion's share of seats in both houses of parliament, dominate the new constitutional assembly and may take the presidency. They are on their way to power much faster than many assumed was possible.
But at what cost to their reputation? At the beginning, the Brotherhood insisted that it would field candidates for only 30 per cent of parliamentary seats. Within weeks, that number steadily increased without any real explanation until it became 50 per cent. Expelling Mr Fotouh and others cost the leadership some popularity within the Brotherhood itself.
But the real discontent was not apparent until the Brotherhood entered parliament. It had made assurances that it would not form alliances with the Salafi MPs, largely represented by the Noor Party - but collaboration took place to assure a predominantly Islamist constitutional assembly.
The latest doubt was raised when the FJP reneged on a pledge not to field a presidential nominee. Khairat Al Shater, a senior leader and the former deputy general guide of the Brotherhood, is now a favourite to win.
These moves were entirely in keeping with the impulse of the FJP. It was not created as the result of the revolution or as a revolutionary force, but simply because of the absence of the Mubarak repression.
One of the consequences is being felt in the internal tensions in the Brotherhood, although it is unclear if these will lead to a real split in the short term. Some within the movement have already expressed objections to Mr Al Shater's nomination, even while saying they will respect the majority's decision.
The scholar Kamal El Helbawy, a former Brotherhood spokesman in Europe, has already resigned, and others may follow. Other famous Islamists have criticised the decision, including Yusuf Al Qaradawi, who is perhaps the movement's most influential living ideologue, based in Qatar.
Outside of the movement, the Brotherhood has lost a good deal of its moral credibility among Egyptians. But, if it can deliver on policy, this may not immediately affect its popularity.
It will have to contend, however, with the perception that the Brotherhood (an unelected body) actually runs the FJP. This is obviously true - it was the Brotherhood's leadership that decided on Mr Al Shater's candidacy, over the objections of the FJP leaders.
There are consequences beyond Egypt's borders. The Syrian Brotherhood, for example, wants to play a role in Syria, but they may find their credibility damaged as a result of events in Egypt. Already some Syrian members are discreetly complaining. Tunisia's Ennahda Party has been far more delicate, but its opponents will also point to the mother movement in Egypt to attack its credibility.
More generally, opponents of Islamist movements from all over the world, Muslim or not, are likely to use the Brotherhood's manoeuvres to claim that Islamist projects are, in themselves, unethical. Islamophobes and others have already smeared the "double talk" of Muslims generally.
For decades, Islamist movements in North America and Europe have been active in civil society and engaged in positive ways with society. Their activism was based on a belief that Islamist projects' ultimate aims were to bring good to people - not to seek power. How will Egypt's schemes affect their movements? Time will tell.
After the death of the founder of the Muslim Brotherhood, Hasan Al Banna, disciples declared that his death meant the death of the Brotherhood - anything that followed was considered almost a perversion of his ideas. For many others, the milestone of the Brotherhood's demise may be linked to the founding of the FJP.
Dr HA Hellyer is a Middle East analyst with experience at Gallup, Warwick University and the Brookings Institution
On Twitter: @hahellyer
Editor's note: This article was amended to specify that Kamal El Helbawy is the former Muslim Brotherhood spokesman in Europe.