Consubstantiation is not Lutheran theology. Lutheran theology rejects consubstantiation in favor of "Sacramental Union" [sacramentatem unionem]. See the Book of Concord, "The Solid Declaration of the Formula of Concord"; Sect. VII "The Holy Supper"; esp. subpara. 38.
Lutheran theology holds that the True Body and True Blood of Christ are present in the Sacrament of the Altar both mystically and physically. "The Solid Declaration of the Formula of Concord [Sect. VII "The Holy Supper"] connects this Mystery with the Incarnation ("... the Word became flesh ... ."). No attempt is made to explain that which "surpasses all understanding." Instead, the doctrine is simply asserted, backed with references to, of course, the Scriptures, and also to "Justin, Cyprian, Augustine, Leo, Gelasius, Chrysostom and others" [ibid, subpara. 37]. The True Body and True Blood of Christ are held to be present physically: "... the Lord's bread in the Supper is His true natural body, which the godless or Judas received with the mouth, as well as did St. Peter and all the saints ... " [ibid. subpara. 33]. Thus we see that the Real Presence of the True Body and True Blood of Christ are held to be present mystically and physically as an objective reality, quite apart from the faith or ideas or notions of those who receive them "orally" and quite apart from the "wickedness" or unworthiness of the priest* who celebrates the Mass* and administers the elements [ibid. subpara. 32]. However, Lutheran teaching also holds that the Sacrament does not "bring justification just by taking part" in it, but rather that "a faith which believes in the forgiveness of sins is needed ..." [See the unaltered Augsburg Confession, Art. XIII, para. 3.].
- (the terms used in the Lutheran confessions)
It is also--how shall I put it?--less than precise to say that Luther and the Lutheran reformers held such things as Corpus Christi processions to be "idolatrous." It is true that Luther used the words "vain idolatry" to refer specifically to Corpus Christi processions, but this was in one of his "Table Talks," not in any "official" writings or in any of the Confessions. Luther died in 1546, but Lutheran calendars retained Corpus Christi until 1600 [See Frank Senn: Christian Liturgy: Catholic and Evangelical, Fortress Press, 1997. p. 344. ISBN 0-8006-2726-1]. Luther's objection was that Christ had instituted the Sacrament of the Altar for specific purposes, and that that purpose was not for processions but for the forgiveness of sins; for awakening and strengthening faith in those who receive it; and for comforting the faithful. The Augsburg Confession [Art. XV "Of Church Customs"] says quite clearly that "Church customs [...] such as holy days, festivals, and the like [...] may be practiced only if they can be used without sinning. [...] But people must be strongly reminded that such customs [are not done] in order to earn salvation" [Augsburg Confession, Art. XV]. This of course, is connected with the Lutheran emphasis on salvation "by grace through faith" and not through works, "lest any man should boast" [Ephesians 2: 8-9].
And this was written by George III, Prince of Anhalt-Dessau and Prince of Anhalt-Plötzkau [1507-1553], priest, and one of the driving forces in the Lutheran Reformation: "Now, here we are not saying that one should not worship our dear Lord Jesus Christ in this Sacrament, being present, or that one should not hold this Sacrament with all honor and reverence. On the contrary, since these divine, almighty, true words are believed, all of this follows of itself, and not only in external gestures but also both externally and, first and foremost, in the heart, spirit, and truth. On account of this, such adoration of Christ is not thereby cancelled, but much rather, confirmed. For where the Word is rightly seen, considered and believed, the adoration of the Sacrament will happen of itself. For whoever believes that Christ's body and blood are there (as there is plenty of evidence so to believe, and it is necessary so to believe), he cannot, to be sure, deny his reverence to the body and blood of Christ without sin. For I must confess that Christ is there when His body and blood are there. His words do not lie to me, and He is not separate from His body and blood."
As to whether Lutheran churches do or do not reserve the consecrated bread as the True Body of Christ, I myself have seen tabernacles containing the Reserved Host in Finland and in Latvia. In Finland, at the cathedrals in Turku and Helsinki; in Latvia at the Cathedral in Riga.