ok i think there are several issues here...
a) genetic food is as harmless or dangerous as any other crop for humans. the claim that this is dangerous for people is rediculous. the panic campain was started in europe by the ecology parties and several environmental orgs. in oder to scare people into voting for them and making donations.
b) genetic food has so far certainly not rescued millions or billions of people. this claim is as rediculous as the first. many modifications serve for instance to make the plants resistant against a specific herbizide. oddly enough the herbizide and the resistant plant are both sold by the same company. monsanto et al. the poor countries that would need crops that can grow faster etc. cannot afford them anyway.
c) the modified crops will make farmers completely dependant on the large pharma corporations which produce these crops. farmers will have to buy the seeds each year from the company.
d) cross pollination can and does cause the modified plants to mix with other plants. this could have in principle serious ecological consequences. for instance to give an exaggerated example if crop A is made resistant against beatle X but the resistance gene gets transferred to all other plants that beatle X can eat than beatle X will die out. this in turn can cause many other species to die out...
but overall the issue is hugely blown out of proportion imo.