ye - who worship idols. The question emphatically implies, they had known.
from the beginning - (Isa 41:4, Isa 41:26; Isa 48:16). God is the beginning (Rev 1:8). The tradition handed down from the very first, of the creation of all things by God at the beginning, ought to convince you of His omnipotence and of the folly of idolatry.