Church membership is defined by The Episcopal Church as follows:

“All persons who have received the Sacrament of Holy Baptism with water in the Name of the Father, and of the Son, and of the Holy Spirit, whether in this Church or in another Christian Church, and whose Baptisms have been duly recorded in this Church, are Members thereof.” (TEC Constitutions and Canons 2024, Title I, Canon 17, Section 1.a)

Click: Becoming a Member of the Episcopal Church