Shirk and its different forms
Will good deeds avail a person anything if he dies as a kaafir?
When does obedience to a created being become shirk akbar?
The kufr of one who rules according to other than what Allaah revealed
Tawassul: Islamic vs. Bid`ah
Tawassul in Arabic means seeking to draw close. There are two types of Tawassul; correct Islamic tawassul and forbidden tawassul. For more, please see the detailed answer.Priest who uses Islam this site for reference
Do Muslims worship Muhammad(peace and blessings of Allah be upon him)