Imagine my surprise then, when reading the Large Catechism, which is in the Book of Concord, I stumbled upon this juicy bit. In the section covering the Fourth Commandment, Luther writes:
158 So we have two kinds of fathers presented in this commandment: fathers in blood and fathers in office. Or, those who have the care of the family and those who have the care of the country. Besides these there are still spiritual fathers. They are not like those in the papacy, who have had themselves called fathers but have performed no function of the fatherly office [Matthew 23:9]. For the only ones called spiritual fathers are those who govern and guide us by God’s Word. 159 In this sense, St. Paul boasts his fatherhood in 1 Corinthians 4:15, where he says, “I became your father in Christ Jesus through the gospel.” 160 Now, since they are fathers, they are entitled to their honor, even above all others. But to spiritual fathers the least amount of honor is bestowed. The way the world knows for honoring them is to drive them out of the country and to begrudge them a piece of bread. In short, spiritual fathers must be (as says St. Paul [1 Corinthians 4:13]) like the filth of the world and everybody’s refuse and foot rag.
161 Yet there is need that this truth about spiritual fatherhood also be taught to the people. For those who want to be Christians are obliged in God’s sight to think them worthy of double honor who minister to their souls [1 Timothy 5:17–18]. They are obligated to deal well with them and provide for them. For that reason, God is willing to bless you enough and will not let you run out. 162 But in this matter everyone refuses to be generous and resists. All are afraid that they will perish from bodily needs and cannot now support one respectable preacher, where formerly they filled ten potbellies. 163 Because of this, we also deserve for God to deprive us of His Word and blessing and to allow preachers of lies to arise again and lead us to the devil. In addition, they will drain our sweat and blood.
164 But those who keep God’s will and commandment in sight have this promise: everything they give to temporal and spiritual fathers, and whatever they do to honor them, shall be richly repaid to them. They will not have bread, clothing, and money for a year or two, but will have long life, support, and peace. They shall be eternally rich and blessed. 165 So just do what is your duty. Let God manage how He will support you and provide enough for you. Since He has promised it and has never lied yet, He will not be found lying to you [Titus 1:2]. (LC I:158–165).There you have it guys. Luther says it's okay. He also says that whatever you do to honor your fathers, temporal and spiritual, "shall be richly repaid." Did I mention that Gottesdienst accepts donations? Too much? Well, at least the quotation's good.