▁explains ▁his ▁the ology ▁is ▁Christ ' s ▁presence ▁in ▁the ▁Church , ▁more ▁specifically ▁in ▁the ▁teaching ▁and ▁pre aching ▁of ▁the ▁faith ▁( Script ure , ▁Trad ition ▁and ▁their ▁interpretation ), ▁in ▁the ▁lit ur gy ▁( s ac r aments ▁and ▁celebr ations ), ▁in ▁the ▁life ▁of ▁the ▁individual ▁bel ie ver ▁and ▁of ▁the ▁organized ▁Church , ▁especially ▁in ▁a ▁council . ▁ ▁To ▁Leo ▁the ▁Great , ▁Mari ology ▁is ▁determined ▁by ▁Christ ology . ▁If ▁Christ ▁were ▁divine ▁only , ▁everything ▁about ▁him ▁would ▁be ▁divine . ▁Only ▁his ▁div inity ▁would ▁have ▁been ▁cru c ified , ▁buried ▁and ▁res ur rect ed . ▁Mary ▁would ▁only ▁be ▁the ▁mother ▁of ▁God , ▁and ▁Christians ▁would ▁have ▁no ▁hope ▁for ▁their ▁own ▁res urre ction . ▁The ▁nucle us ▁of ▁Christian ity ▁would ▁be ▁destroyed . ▁The ▁most ▁unusual ▁beginning ▁of ▁a ▁truly ▁human ▁life ▁through ▁her ▁was ▁to ▁give ▁birth ▁to ▁Jesus , ▁the ▁Lord ▁and ▁Son ▁of ▁King ▁David . ▁ ▁He ir ▁of ▁Peter ▁Leo ▁assumed ▁the ▁pap acy ▁at ▁a ▁time ▁of ▁increasing ▁bar bar ian ▁invas ions ; ▁this , ▁couple d ▁with ▁the ▁decre asing ▁imperial ▁authority ▁in ▁the ▁West , ▁forced ▁the ▁Bishop ▁of ▁Rome ▁to ▁take ▁a ▁more ▁active ▁part ▁in ▁civ ic ▁and ▁political ▁affairs . ▁He ▁was ▁one ▁of ▁the ▁first ▁b ish ops ▁of ▁Rome ▁to ▁promote ▁pap al ▁prim acy ▁based ▁on ▁succession ▁from ▁Peter ▁the ▁Apost le ; ▁and ▁he ▁did