This is what happens when you confuse the meaning of a word with its origin. Here is the definition of “terrorism,” from the Oxford English Dictionary, 2d ed.:

1. Government by intimidation as directed and carried out by the party in power in France during the Revolution of 1789–94; the system of the ‘Terror’ (1793–4): see terror n. 4.

2. gen. A policy intended to strike with terror those against whom it is adopted; the employment of methods of intimidation; the fact of terrorizing or condition of being terrorized. Also transf. Cf. terrorist 1b.

President Bush uses the term in the second sense—to refer to those whose avowed aim is to destroy us. Robespierre was not the George W. Bush of his day; he was the Osama bin Laden of his day.