The best illustration I like to use is the one with a cup and a pitcher (and remember, please do not overdo this illustration, or you will destroy it). God is like a never-emptying pitcher. We are like empty cups. Every time we make use of the means of grace, hearing the Word read and proclaimed, reading the Word on our own, remembering our Baptism, participating in the Lord’s Supper, confessing our sins and being given absolution-whenever we do these things, the Lord fills us, our cups, from His never-emptying pitcher.
We could come and be filled and then go away and not return to be given any more gifts, but just as a cup of water will eventually become dry as the water evaporates, we could eventually lose any gifts we have been given. We could return time and again, yet with a larger cup each time so that we are never filled with our Lord’s gifts. Or we could make regular and diligent (every Sunday and every day) use of the means of grace and be filled and filled some more until we are overflowing and the gifts God gives to us spill out from us onto others. In other words, our faith overflows as we share it with others. This devolvement is also a response of faith, that is, doing the good works which God has for us to do (Ephesians 2:10; James 2:14).
Thus, we see the importance of our own participation in the means of grace as a witness to others of what is important in our own lives and as a means through which our Lord comes to fill us, to give us His good gifts and blessings. Through such grace (God’s grace), then, we are strengthened and kept in faith and are better able to give an answer for the hope we have in Jesus our Savior.