This is the most serious of all prohibitions, according to the hadeeth narrated by Abu Bakrah, who said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘Shall I not tell you of the most serious of the major sins?’ three times. We said, ‘Of course, O Messenger of Allaah!’ He said, ‘Associating anything in worship with Allaah . . .’”
(Agreed upon; see al-Bukhaari, no. 2511, al-Bagha edition).
Every other sin may be forgiven by Allaah, apart from shirk, which requires specific repentance, as Allaah says (interpretation of the meaning):
“Verily, Allaah forgives not that partners should be set up with Him in worship, but He forgives except that (anything else) to whom He pleases . . .” [al-Nisaa’ 4:48]
Unfortunatelly there are many forms of shirk found even amoungst the Muslims due to their ignorance of Islam, wanting to cling onto customs of their fore fathers religion or traditions, or even because of their desire to make a new Islam. thus showing disrespect to both Allah and His Messenger Muhammad . May Allah protect us from Shirk and those who promote it . Ameen