You can read about it from the horse's mouth. (And I do not wish to make a habit of contradicting kleinb100, but it is in fact called Globalism by its propents. Neo-Liberalism is the 'theoretical' framework that supports the political front of Globalists.)
There are three general fronts opposing globalism: conservative, theoretical, and conspirational.
The conservative group -- whether cultural or political -- is opposed by the self evident fact that globalism will by necessity entail the erosion of national integrity (nationalism here meaing in essence that your life for better or worse is mainly impacted by your own nation's features, culture, politics, trends, etc., which in a democratic nation means you have some say in it).
The theoretical group objects to the neo-liberal (economic) and neo-con (martial) framework, by objecting to the reduction of all politics to mere economics ("end of history"); and the wars necessitated by the push to 'remove' (regime change) nations that stand in the way per the neo-con policy.
The conspirationist share some (or all, depending on the tin foil envelope) of above, but go further in asserting that globalism is not motivated by the overt neo-liberal ideology but is in fact a nefarious plan to affect a gray universal culture and entirely strip the mass of humanity of our cultural and political will, and reduce us to "slaves" in the grand global plantation of a few wealthy families that subverted Europe starting in 16th century. Typically, but not necessarily, this gets reduced to (or slandered as per your pov) as anti-semitism given that the said families are banking families of Rothschilds and the Rockefellers.
So you will find that conservative and conspirational opposition are highly sensitive to efforts to dismantle standing cultural institutions such as religion, family, sexual norms, etc. They view it -- and this is actually fairly supported by human history -- as a 'device' to reduce the individual into a highly programmable 'unit' in the larger socio-economic regime. Recent examples that these two fronts cite are the collectivist tyrannies of Soviet Union and Maoist China.
The theoretical front is keenly sensitive to the transfer of political power to trans-national corporations (institutionalized in secret treaties such as TPP).
My personal view is that some form of united Humanity is certainly inevitable short of some natural disaster or global conflict that would dismantle the current civiliation and sends us back to caves and the proverbial drawing board.
But I equally believe that the current self-elected global elite are entirely unsuited -- in terms of moral, intellectual, and administrative deficits -- to lead an unwilling (and I should add, not yet ready) humanity to such a union at this point in time.
Anyway, that is my 2cents and hope it is informative.