Robert O. Paxton, a professor emeritus at Columbia University, defines fascism in his book The Anatomy of Fascism as: "A form of political behavior marked by obsessive preoccupation with community decline, humiliation or victimhood and by compensatory cults of unity, energy and purity, in which a mass-based party of committed nationalist militants, working in uneasy but effective collaboration with traditional elites, abandons democratic liberties and pursues with redemptive violence and without ethical or legal restraints goals of internal cleansing and external expansion."
It should be clear that there is nothing fascist about "Islamofascism," so that's an example of people using the fascist label as a means of attack rather than as a serious description. Fascism is more like a religion than it is like a political movement. Fascism isn't motivated by rational conclusions about economics, political philosophy, or social policy. This makes real religions like Christianity well suited for integration with a fascist movement. If fascism occurs in America, it will be Christian in nature because only Christianity has the power to motivate a mass-based movement with a passionate concern for unity, redemption, victimhood, and nationalism. Christian fascism will also be convinced of its own righteousness, moral purity, and godly intentions.
This image was taken from a World War II poster of an American prisoner of war saying "Don't Let Me Down" and "You are still free to work." Americans are free to work, but how free are they to enjoy the rest of the liberties which Americans fought and died to protect in World War II? Overt repression in America hasn't started, but once a people unjustly puts others in shackles, they put on their own shackles as well. One is imprisoned by the brutality of the other; the latter is imprisoned by the need to perpetuate their own brutal methods lest the repressed rise up.
There are reports of President Bush claiming that he was chosen by God to be president during this time in history. There are also reports of Bush claiming that he speaks to God, with God giving him instructions on foreign policy -- including the invasions of Afghanistan and Iraq. If Bush were alone in this it might simply be dismissed as egotistical delusions, but many of Bush's Christian supporters completely agree. They believe that Bush was placed in office by God, that Bush's authority is derived from this divine mandate, and that Bush's policies are all the Will of God.
If people believe their leader is placed in charge by gods, they are less likely to question, challenge, or oppose his decisions. This is what makes such beliefs popular with authoritarian, totalitarian, theocratic, and fascist rulers; it's also what makes such beliefs inimical to democratic systems. If God, not the people, is the sovereign power responsible for Bush being president, then it means Bush is ultimately responsible to God rather than to the people. Democracy requires the principle that citizens, not gods, choose their leaders and that the government is founded on human reason rather than divine agency.
This is fertile ground for Christian Nationalism and Christian Fascism because it allows for the excision of democracy, democratic elections, the separation of powers, constitutionally protected rights, and everything else which makes America a secular and free nation. People who say that Bush was placed in office by God are denying that Bush's authority and office derive from the will of the people. People who say that Bush is doing the Will of God are denying that the American people have any right to challenge or stop Bush. All of this is unequivocally anti-democratic.