http://islam-watch.org/AbulKasem/BismiA ... _final.htm
Idolatry is an unforgivable crime in Islam. Islam shows no mercy to idolaters.
However, Allah’s mind is too complex. At times, He does indeed forgive the idolaters. In Qur’an we read that Allah did forgive Moses people for reverting to shrik (idolatry).
God dazed people with thunder and lightning (miracles of God) for asking Moses to show them God in public; God forgave the calf worshippers (i.e., God forgives shrik, idolatry; also see 2:55, 56, 17:90)...4:153
[4.153] Ahli Kitab meminta kepadamu agar kamu menurunkan kepada mereka sebuah Kitab dari langit. Maka sesungguhnya mereka telah meminta kepada Musa yang lebih besar dari itu. Mereka berkata: "Perlihatkanlah Allah kepada kami dengan nyata". Maka mereka disambar petir karena kelalimannya, dan mereka menyembah anak sapi, sesudah datang kepada mereka bukti-bukti yang nyata, lalu Kami maafkan (mereka) dari yang demikian. Dan telah Kami berikan kepada Musa keterangan yang nyata.
To complicate matters, Allah even admits that he loves the sinners
(including the idolaters, perhaps). In a hadith we read:
Allah needs sinners… (Sahih Muslim 37.6620, 6622)
Sahih Muslim, Book 037, Number 6620:
Abu Sirma reported that when the time of the death of Abu Ayyub Ansari drew near, he said: I used to conceal from you a thing which I heard from Allah's Messenger (may peace be upon him) and I heard Allah's Messenger (may peace be upon him) as saying: Had you not committed sins, Allah would have brought into existence a creation that would have committed sin (and Allah) would have forgiven them.
Sahih Muslim Book 037, Number 6622:
Abu Huraira reported Allah's Messenger (may peace be upon him) having said: By Him in Whose Hand is my life, if you were not to commit sin, Allah would sweep you out of existence and He would replace (you by) those people who would commit sin and seek forgiveness from Allah, and He would have pardoned them.