What is the way to gain deep understanding of the religion, given the multitude and divergence of groups that have corrupted it?

Seeking religious knowledge is an act of worship by which one draws closer to Allah, and it is of two types: obligatory (fard) and supererogatory (nafilah). The obligatory type includes learning the prescribed religious duties (such as prayer, fasting, pilgrimage, and zakat (definition)), matters of monotheism and faith, and rulings concerning transactions for those who engage in them. This much is obligatory upon every Muslim man and woman. If a Muslim cannot find this knowledge in their land, it becomes obligatory for them to travel in search of it. Knowledge should be sought from trustworthy individuals known for their knowledge, righteousness, and adherence to the Sunnah (definition), while avoiding innovators. One can benefit from the books and explanations of well-known scholars such as Shaykhs Ibn Baz and and Al-Uthaymeen.