Final answer:
Grace in Christian theology is a free favor from God that heals human nature from sin and allows unity with the Divine. It originates from the sacrifice of Christ and is continuously present in sacramental practices such as the Eucharist.
Step-by-step explanation:
The gift described in the question is grace, a central concept in Christian theology. Grace is seen as a free and unmerited favor of God, which enables humans to participate in the intimate life of the Trinity, as well as to restore the human nature that has been wounded by sin. This belief is rooted in the Christian understanding of the sacrifice of Jesus Christ, His death and resurrection, which opened the door to eternal life and restored the broken relationship between God and humanity caused by original sin. The idea of grace also encompasses the incarnation of Jesus, as explained in Christianity, where God became human in the form of Jesus Christ for the salvation of the world. Moreover, the sacramental life of the Church, including the Eucharist, reflects the ongoing presence of this grace, as the bread and wine are believed to become the body and blood of Christ, a reflection of His sacrifice and love for humanity.