Answered by Ustadh Salman Younas
Question: 1. Must we have no doubt whatsoever in order to stay within the folds of Islam? Is doubt allowed as long as you don’t affirm it as your central belief?
2. Does someone dying in a state of drunkenness or from a drug overdose dies as a disbeliever?
Answer: assalamu `alaykum
1. Such a person would still be deemed a believer. Having “doubts” is inconsequential to one’s faith unless one actually accepts them in a manner that entails rejection of the core beliefs of Islam.
In fact, doubts about aspects of faith is natural and simply part of the struggle that a believer must undergo. The Companions themselves experienced such doubts when they confided in the Prophet (God bless him), “We have thoughts that any of us would consider too enormous to even mention.” The response of the Prophet (God bless him) was this was a sign of the purity of their faith. [Muslim, Sahih]
In such situations, it is important to seek refuge in God, thank Him for the blessing of faith, and anchor oneself in the religion through study and spiritual practice.
For more on this, see:
What is the Ruling For Someone Who Has Thoughts of Disbelief Without Saying Them Aloud?
Tormented by Thoughts of Disbelief
How Can I Regain My Faith After Doubts and Exploring Other Religions?
Doubts About Islam: I Don’t Find Any Observable Effect or Peace in My Worship
2. These are all major sins but their perpetrators are still considered believers.
The default is that one only exits from the faith through rejecting that which brought him into it as Imam al-Tahawi and others stated. In other words, committing certain impermissible actions is generally deemed insufficient a reason to consider someone outside the fold. This is a very prominent position upheld by the Sunni majority in opposition to other sects, like the Khawarij.
For more on the principles of disbelief, see the first heading here: What Are the Consequences of an Oath of Disbelief?
Checked & Approved by Shaykh Faraz Rabbani