What is one important factor that led to the defilement of true worship, and what significant doctrine came to the fore?
٩ مَا هُوَ أَحَدُ ٱلْعَوَامِلِ ٱلرَّئِيسِيَّةِ ٱلَّتِي أَدَّتْ إِلَى تَدْنِيسِ ٱلْعِبَادَةِ ٱلْحَقَّةِ ،‏ وَأَيُّ عَقِيدَةٍ مُهِمَّةٍ تَأَثَّرَتْ بِذلِكَ ؟‏