It does not mean Muslims are exempted from God's punishment; none is exempted; so man should ward off the disobedience particularly and before everything else: avoid the atheism, disbelief, idolatry, wrong-doing, transgression and the other commandments contradiction.
E.g. even prophets are punished in a way or another .. like
Prophet David when he sent the captain in his army to a dangerous battle so that he might be killed and then he would marry his widow following his killing .. of course he waited until her 'idda' or the prescribed period for marriage and then he married her .. this was a disobedience, but Prophet David repented at once and did not insist on his sin like sinners .. then Prophet David was punished .. his first son died (before the birth of Solomon)
Also
Prophet Mohammed was threatened by God lest he might relent or yield to the suggestions of the idolaters and accept a compromise request; so Prophet Mohammed at once refused their request and ordered all the idols be broken up; refer to
this aya and its explanation:
Quran 17: 73-75, which mean:
73. The [associaters or idolaters] were about to tempt you [Mohammed] away from [the commandment] that We revealed to you; so that you might forge against Us other [words, and say: God commanded that.]
They – then – would certainly take you as their dear friend [because you would grant them what they want.]
74. And had We not confirmed you [Mohammed], surely you were about to incline to them a little bit.
75. In that case [if you had responded to their request], We would have let you taste a double [portion of the punishment] of living and a double [portion of the punishment] of dying; and moreover you would not have had – against Us – any helper.
http://quran-ayat.com/pret/17.htm#a17_74
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quran-ayat.com/pret/17.htm#a17_74>
And
Moses was warned by God so as he would not listen to the hypocrites among his people.
And
Noah was warned by God that he should not intercede for the idolaters even to his son Canaan.
And
Jonah was punished when the whale engulfed him so as to swallow him, but he repented and was pardoned.
And
Jesus was instructed that he should remember God's grace on him.
And
Abraham was told to desist from disputing about the punishment of the people of Lot.