Different disciplines have explored the history of Islam in Yoruba land which
started in the early 18th century. However, the impact of religious syncretism has
not been systematically studied. Therefore, this thesis examines the extent of the
involvement of Yoruba Muslims in syncretic beliefs and practices in Nigeria using
the Lagos State as a case study, with a view to bringing out the impact of Tawh?id on
them. In agreement with previous research, this study notes that there is a
prevalence of religious syncretism among many Yoruba Muslims, but it principally
argues that its impact affects many of them negatively. If continuous awareness
campaign could be carried out, the phenomenon will be reduced. A triangulated
method was used to carry out this study. The findings of this thesis indicated
reappraisal of the problem associated with many Yoruba Muslims’ persistence in
syncretism and its implications on their faith (iman). While this study appreciates
the attempts of some scholars to eradicate this endemic problem, it reveals that
Tawh?id is not yet inculcated into many Yoruba Muslims within the Yoruba religiocultural
context. Therefore, a concerted effort is necessary among all stakeholders
in the task of promoting the effective instillation of practical Tawh?id.