A couple quotes about the sacraments.
“In His sovereignty God has bound Himself to impart His grace not on account of our use of the means, but along the route of the means that He has prescribed for us” (Herman Bavinck, Saved By Grace, 102).
“Nature and grace are distinct, yet they do not stand detached from one another. The same God who regenerates His elect in Christ through the Holy Spirit is the one who, as Creator and Sustainer, cares for them and leads them also to the moment when He visits them with His grace. Therefore the means of grace are not superfluous; and how we make use of them is not an insignificant matter. . . . For grace is imparted by means of warnings; and to the degree that we perform our obligation readily, to that degree will the benefit of God who works in us be the more excellent” (154).
God has freely and sovereignly bound Himself to work in us and impart grace through the means that He has prescribed. Believers partake of God’s grace by the means of grace, indeed.