There are three things i want to say. These are just observations, not definitive claims.

1. 'Mabus' by no means qualifies to be the name of the 3rd antichrist. Not even close. Rather, after his (Mabus) 'death' the trouble will start (according to Nostradamus). And the end war will actually be led by an active, living antichrist. So mabus cant be the antichrist.

2. Nostradamus at least 3 times uses the hint 'Noir' in association with the antichrist. Observe Q III.LX , Q IV.XLVII and Q VI.LXXXI. Now taken in context with Obama, it comes scarily close, as noir literally means 'Black' or 'Dark'. Food for thought perhaps this one.

3. Gog and Magog prophecies. As Armageddon relates to Gog and Magog, and armageddon relates to the antichrist, so perhaps the Antichrist directly relates to Gog and Magog? According to the most agreed upon concept, Gog and Magog were from Central Asia (Russia) in the past, so perhaps they again have a role in the future. If so, this places the advent of the antichrist from Central Asia.

As for being sure, nobody's sure. But obama could be it, coz this guy obviously is a hypocrite. We still dont know what his true religion is, is he a muslim or a christian or just a pretender? And he's so at ease with these contradictions in him, points towards a criminal mind. But again, no claims can be made and his being the antichrist can very easily be argued against.