Maran Harav Hutner Ztz"l said that the apikorsim [heretics] of our time "reden andresh ve amolega apikorsim." [Speak differently than the apikorsim of the past.] He explained with a moshol.
There are two ways of creating a revolution against a Monarchy. In Russia the Communists unseated the Czar. They completely nullified the position of king. In England there is still a Kingdom [or at least a Queendom]. But the King lacks all power.
In the olden days the apikorsim said that there is no G-d [like the Russian Revolution]. Today many people believe that G-d exists but it is only a honorary position without true power [as in England].
Kabbalas Ol Malchus Shomayim means to accept Hashem as the ruling King invested with all the power of Kingship.
עד אחד נאמן באיסורים here.