To receive the Eucharist in the state of mortal sin is to commit a sacrilege which is a mortal sin that is directed at God. St. Paul writes: " Therefore whosoever shall eat this bread or drink the chalice of the Lord unworthily, shall be guilty of the body and blood of the Lord. 1 Cor:11:27
However, direct sins against God (Hatred of God, blasphemy of God) and against the humanity of Christ (Crucifixion, betrayal by Judas) are, however, objectively more grevious sins than the profanation of the Sacrament of the body and blood of Christ–according to St. Thomas Aquinas. ( Summa. Theo. III, 80, 5-)
Fr. Vincent Serpa, O.P.