Baptist ecclesiology fosters agency because it is grounded in covenant participation. The triune God invites persons into covenant relationship with God and one another, reflecting an agency-affirming vision of divine–human communion. Baptism embodies this invitation as the believer’s voluntary “yes” to God and the covenant community. Yet agency extends beyond baptism into shared discernment, mutual accountability, and covenant renewal at the Lord’s Supper. While rooted in Scripture, this vision resonates with social-scientific insights about human flourishing. Science-engaged theology—especially Basic Psychological Needs Theory—offers a lens for evaluating whether Baptist communal practices truly reflect the conviction that God desires the flourishing of our gathered communities.