The sacraments of baptism and the Lord’s supper are distinct means of grace; the number of times we receive them, the grace we receive through them, and the time in our life and spiritual development that we receive them worthily differ.
To suggest otherwise confuses their purpose, detracting from them and the blessing they give.
Donald Maclean posts at Meet The Puritans on John Knox’s view regarding those who are qualified to share in the Lord’s Supper.
If the Lord’s Supper is a great blessing, then who should partake of it? In this sacrament, ordained of God, who should come to the table of the Lord? Knox was abundantly clear: “But the Supper of the Lord, we confess to appertain to such only as be of the household of faith, [and who] can try and examine themselves as well in their faith as in their duty towards their neighbours” (Scots Confession in Reformed Confessions, 2:204). It is only those who are “in Christ” and of age to examine themselves who should partake of the Lord’s Supper.
Knox focused often on the need for self-examination. He held that the Lord’s Supper should be partaken of “with all reverence, examining ourselves diligently before” (Scots Confession in Dennison, Reformed Confessions, 2:202.) Knox believed this should be done “because we are assured by the mouth of the apostle that such as eat of the bread and drink of that cup unworthily are guilty of the body and blood of the Lord Jesus” (Scots Confession in Reformed Confessions, 2:202). Paul, Knox noted, exhorted “all persons diligently to try and examine themselves before they presume to eat of that bread and drink of that cup” because “the danger [is] great if we receive the same unworthily, for then we be guilty of the body and blood of Christ our Saviour, we eat and drink our own damnation, not considering the Lord’s body” (Works, 4:192).
Read the whole post.