mmys:
Of course the Zionists managed to fool lots of people at the time. They still manage to fool people even with the benefit of hindsight of history and the recorded clear opinions of the gedolim on this subject.
The Brisker Rav wrote that the State only came into being because of the Jews who davened for that State instead of davening for the geula, which Hashem would have given them at the time had they instead done so. So your post is not a chidush.
But whatever your grandfather’s opinion is, or that of others who were there, one can presume that both the Brisker Rav and Chazon Ish were greater than he and the others.
Both the Brisker Rav and Chazon Ish agreed that the state’s establishment was a gizeirah raah. The Brisker Rav pointed out to the Chazon Ish that a gizeirah (raah) avida liHibatla only applies when people understand that it’s a gezeira raah so he feared that this gizeirah would remain ad beas goel, Hashem yiracheim.
On a subsequent Israeli Independence Day, the Chazon Ish was honored with Sandak for three brisos. Despite this, he insisted on saying Tachanun that morning anyways so that nobody would make any mistake about this matter.
But the “Religious Zionists” continue to delude themselves and attempt to delude others who don’t know any better.