You said, "To hypothesize beyond the warning given, is foolish."
That is exactly right! Dr. MacArthur was responding to a hypothetical question that dealt with the single act of taking the mark and excluded "worship". And the second part of the hypothetical substitutes the "lost" with the elect or the saved. To be clear, the verse in question is dealing with the lost, not the saved or the elect who were substituted as the "subjects" for purposes of the hypothetical.
I have yet to see you or any of your friends take these known facts into consideration. And I have not seen any of you friends conclusions address the hypothetical presented in terms of their beliefs being in direct conflict with Matthew 12:31
"Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy against the Holy Ghost shall not be forgiven unto men."
Simply put, the verse deals with the lost and as you would expect they worship the beast, the idol "AND" take the mark.
The hypothetical excludes the worship of the beast and the idol. It hypothesizes that a believer or one of the elect (for some unspoken reason) takes the mark.
The hypothetical question posed now asks if a believer takes ONLY the mark, can they be forgiven? Under these set of conditions Matthew 12:31
Your fractured fairy tale of Dr. MacArthur teaching heresy is beyond a quantum leap in logic and reeks of an attempt to not only defame a great man but to call Christ a liar. That is quite a price to pay in order to satisfy your ill intent!