So how do Catholics receive grace? Is it through the Eucharist?
—So how do Catholics receive grace? Is it through the Eucharist?—
Normatively, through all of the Sacraments. A distinction can be drawn between Baptism and Penance, which confer initial sanctifying grace, and the others that increase sanctifying grace within us.
Also, we believe that God is not bound by the Sacraments, and may dispense His grace as He sees fit. But Catholics can be certain of receiving grace through the sacraments, as long as we are properly disposed.
We also believe that non-Catholics may receive sanctifying grace:
The Catholic Encyclopedia (1913)
“The Catholic Church has ever taught that nothing else is needed to obtain justification than an act of perfect charity and of contrition. Whoever, under the impulse of actual grace, elicits these acts receives immediately the gift of sanctifying grace, and is numbered among the children of God. Should he die in these dispositions, he will assuredly attain heaven.”
Also, “Jesus Christ by His passion and death gave to the sacraments the power of conferring grace.”
Ref. Catechism of Pope St. Pius X