After the church was established

After Alma had organized the Church in Zarahemla and ordained priests
and elders to preside and watch over the Church, he established a
missionary program among the church members. Members showed concern
for non-members by fasting and praying on their behalf. Alma 6:6
says: "Nevertheless the children of God were commanded that they
should gather themselves together oft, and join in fasting and mighty
prayer in behalf of the welfare of the souls of those who knew not
God."