Maybe their opposition is becuase of the heretics who have taken control over Israel. Many Jews believed that since many of the zionists were athiests and not religious Jews the whole movement would fail. Also theirs something about good cant can from something bad, aka you cant do a mitzva from an avera.
Thier are different opinions, everyone has their way of learning and applying, whats important is to try to present your arguments in a respectful way and to regognize that their are differences in Torah law, and each Jew should find himself a Rav and follow him. (every page of the Talmud has a Mahloket- but whats the difference between the giants then and from many people now is that it wasnt personal, and not full of hate,etc.)