Background Prior research on spirituality in cancer survivors has often failed to distinguish the specific contributions of faith, meaning, and peace, dimensions of spiritual wellbeing, to quality of life (QoL), and has misinterpreted mediation analyses with these indices. Purpose We hypothesized a model in which faith would have a significant indirect effect on survivors' functional QoL, mediated through meaning and/or peace. Methods Data were from the American Cancer Society's Study of Cancer Survivors-II (N=8405). Mediation analyses were conducted with the Functional Assessment of Chronic Illness Therapy-Spiritual Well-being Scale (FACIT-Sp) predicting the mental component summary (i.e., mental functioning) as well as the physical component summary (i.e., physical functioning) of the SF-36. Results The indirect effect of faith through meaning on mental functioning, 0.4303 (95 % CI, 0.3988, 0.4649), and the indirect effect of faith through meaning and peace on physical functioning, 0.1769 (95 % CI, 0.1505, 0.2045), were significant. Discussion The study findings suggest that faith makes a significant contribution to cancer survivors' functional QoL. Should future longitudinal research replicate these findings, investigators may need to reconsider the role of faith in oncology QoL studies.