The aim of the study was to find out the causes of Lay women marginalization as they perform socio-spiritual roles in Christian churches in Kisii central sub county in Kenya and their effects to the Christian churches. The study design was cross- sectional survey that was performed in Kisii County Sub-county in Kenya. Self-administered questionnaire were administered to 375 Lay church members and 34 to Christian church leaders. Data was collected and analyzed descriptively so as to find out the causes of marginalization among the Lay women in Christian churches and their effects. The study outcome showed that their numerous causes of women marginalization in Christian churches which affects the church growth, it was also noted that the causes of Lay women marginalization varied from one denomination to the other due to differences in social, economic and political situations where the churches are located. Lay women empowerment on how they can participate fully in performing social-spiritual roles in Christian churches needs to be enhanced. There is need for cultivation in order to create doctrines that practices that advocates for equality of both gender in the church.