Spiritual Development: An Interdisciplinary Study. Loyola University Press, 1987.

This book is out of print but is available through used book stores or in libraries.

From the Introduction :

Traditional theology and spirituality describe stages in the spiritual life, the notion of a path, a journey, a process, a developmental sequence.

Contemporary psychology also speaks of human life in terms of development, but with the rigor of a methodical science.

If spiritual development were conceived as human development viewed according to a particular set of concerns, the stage theories of psychology could significantly contribute to defining systematic stages of spiritual development. Then spiritual development would stand with other psychologically defined conceptions of human development: Kohlberg's moral development, Fowler's faith development, and Loevinger's ego development. That is the hypothesis pursued in this essay.

Acceptance of that hypothesis necessitates separate treatment of the psychological and theological questions. Accordingly, this book falls into three parts.

Part I critically reviews the psychological literature on spiritual development, develops a definition of spiritual development, reviews the psychological stage theories of human development, and finally suggests a summary understanding of spiritual development and its stages.

Part II turns to the question of God and theist faith. The suggestion is that theist faith adds a further dimension of meaning to even an adequate psychological understanding of spiritual development. This contribution is theoretical; it helps explain the matter. But it implies no changes in an adequate psychological understanding of spiritual development. Granted that God exists and that God is active whether acknowledged or not, theism as such offers no special answers to practical questions about the how's and why's of spiritual growth. The psychological account already provides the answers to such practical questions.

Part III treats the still further question about specifically Christian faith and its contribution to a comprehensive understanding of spiritual development. The distinctive contribution of Christian belief is the understanding that human life is a process, not only of human growth, but also growing participation in divine life: deification.

This essay is a theoretical study. It is an attempt to situate in one comprehensive account a variety of issues that all impinge on "spiritual development." As with every theoretical study, the present one is not without far-reaching practical implications. It is vitally relevant to anyone's interest in spirituality.