No it isn't. A belief is not slander.
There are certainly problems with Obama's statement, but that it implies the future doesn't belong to Christians is not one of them.
In that context, a Christian speaking freely as he believes will be deemed by muslims to be insulting, blasphemous, and worthy of death. Thus, in the world painted by Obama, American Christians are either to be stripped of their right to free speech, or second-class dhimmitude. Hence, Barack is clearly siding with Muslims and very much against American Christians, from whom he would take their very future!
With this speech, advocating the loss of Americans' free speech right, Obama is cashiering his Oath of Office and delared himself to be worthy thereby of impeachment and removal as our president (even above and beyond his unworthiness due to his fraudulent usurpation).
HF