In theory, there is nothing in the Augsburg Confession to make it illicit, but the general Lutheran argument in the past was "there is nothing in the Bible to say it would be effective or meaningful to do so" and that the practice was subject to abuse. All of which seem like weak arguments (the Eucharist itself can be subject to abuse, and Scriptures are silent on many things we take for granted).
Huh?
"The invocation of saints is also one of the abuses of Antichrist conflicting with the chief article, and destroys the knowledge of Christ. Neither is it commanded nor counseled, nor has it any example [or testimony] in Scripture, and even though it were a precious thing, as it is not [while, on the contrary, it is a most harmful thing], in Christ we have everything a thousandfold better [and surer, so that we are not in need of calling upon the saints]. And although the angels in heaven pray for us (as Christ Himself also does), as also do the saints on earth, and perhaps also in heaven, yet it does not follow thence that we should invoke and adore the angels and saints, and fast, hold festivals, celebrate Mass in their honor, make offerings, and establish churches, altars, divine worship, and in still other ways serve them, and regard them as helpers in need [as patrons and intercessors], and divide among them all kinds of help, and ascribe to each one a particular form of assistance, as the Papists teach and do. For this is idolatry, and such honor belongs alone to God. For as a Christian and saint upon earth you can pray for me, not only in one, but in many necessities. But for this reason I am not obliged to adore and invoke you, and celebrate festivals, fast, make oblations, hold masses for your honor [and worship], and put my faith in you for my salvation. I can in other ways indeed honor, love, and thank you in Christ. If now such idolatrous honor were withdrawn from angels and departed saints, the remaining honor would be without harm and would quickly be forgotten. For when advantage and assistance, both bodily and spiritual, are no more to be expected, the saints will not be troubled [the worship of the saints will soon vanish], neither in their graves nor in heaven. For without a reward or out of pure love no one will much remember, or esteem, or honor them [bestow on them divine honor]."
The Smalcald Articles
"But the Scripture teaches
not the invocation of saints or to ask help of saints, since it sets before us the one Christ as the Mediator, Propitiation, High Priest, and Intercessor."
Augsburg Confession
"Even supposing that the saints pray for the Church ever so much, yet it does not follow that they are to be invoked; although our Confession affirms only this, that Scripture does not teach the invocation of the saints, or that we are to ask the saints for aid."
Defense of the Augsburg Confession
"Here the adversaries first bid us invoke the saints, although they have neither God's promise, nor a command, nor an example from Scripture. And yet they cause greater confidence in the mercy of the saints to be conceived than in that of Christ, although Christ bade us come to Him and not to the saints."
Defense of the Augsburg Confession
"But where has this arrangement, to which he refers when he says that we ought to resort to the aid of the saints, been instituted by God? Let him produce an example or command from the Scriptures. Perhaps they derive this arrangement from the courts of kings, where friends must be employed as intercessors. But if a king has appointed a certain intercessor, he will not desire that cases be brought to him through others. Thus, since Christ has been appointed Intercessor and High Priest, why do we seek others? [What can the adversaries say in reply to this?]"
Defense of the Augsburg Confession
"Since, therefore, the adversaries teach us to place confidence in the invocation of saints, although they have neither the Word of God nor the example of Scripture [of the Old or of the New Testament]; since they apply the merits of the saints on behalf of others, not otherwise than they apply the merits of Christ, and transfer the honor belonging only to Christ to the saints, we can receive neither their opinions concerning the worship of the saints, nor the practise of invocation. For we know that confidence is to be placed in the intercession of Christ, because this alone has God's promise. We know that the merits of Christ alone are a propitiation for us. On account of the merits of Christ we are accounted righteous when we believe in Him, as the text sa
ys, Rom. 9:33 (cf. 1 Pet. 2:6 and Is. 28:16): Whosoever believeth on Him shall not be confounded. Neither are we to trust that we are accounted righteous by the merits of the blessed Virgin or of the other saints."
Defense of the Augsburg Confession