In Called by God: Discernment and Preparation for Religious Life, Rachael Marie Collins provides an overview of the spiritual life—both its joys and its challenges—and guides women as they discern whether they are called to be religious sisters or nuns.

In a series of letters written by the author to a trusted friend discerning whether to enter religious life, Called by God explores both discernment and spirituality. The key to discernment, Collins argues, is to prepare for religious life by entering deeply into a life of prayer and sacrifice so that one experiences and begins to understand the "work" of a religious before entering the convent.

Called by God draws heavily on the wisdom of great Catholic women such as Teresa of Ávila, Thérèse of Lisieux, Zélie Martin, Edith Stein, Teresa of the Andes, Elizabeth of the Trinity, Miriam Teresa Demjanovich, Elizabeth Leseur, and Caryll Houselander, among others.

Women discerning a vocation will benefit immensely from the discussions about the difference between religious life and marriage, the nature of a vocation, the supernatural superiority of religious life, and spiritual motherhood in Called by God.