The Importance of Correcting the Tawheed First

He says: Honorable Sheikh, may Allah grant you success. Is the weakness and defeat that has befallen the Muslims now because of the weakness in Tawheed or due to increase in desires (sins)? And which one should be corrected and treated first? The Sheikh: Tawheed must be corrected because it is the fundamental and basis (of Islam) As for being occupied with other matters; in forbidding sins and other transgressions, while the Aqeedah is corrupted, your efforts and search are in vain. Correct the Aqeedah first, then correct the mistakes of the people.