Apology of the Augsburg Confession XXVII (XIII): Of Monastic Vows
... There is, moreover, a two-fold forsaking. One occurs without a call, without God's command; this Christ does not approve, Matt. 15, 9. For the works chosen by us are useless services. But that Christ does not approve this flight appears the more clearly from the fact that He speaks of forsaking wife and children. We know, however, that God's commandment forbids the forsaking of wife and children. The forsaking which occurs by God's command is of a different kind, namely, when power or tyranny compels us either to depart or to deny the Gospel. Here we have the command that we should rather bear injury, that we should rather suffer not only wealth, wife, and children, but even life, to be taken from us. This forsaking Christ approves, and accordingly He adds: For the Gospel's sake, Mark 10, 29, in order to signify that He is speaking not of those who do injury to wife and children, but who bear injury on account of the confession of the Gospel.  For the Gospel's sake we ought even to forsake our body. Here it would be ridiculous to hold that it would be a service to God to kill one's self, and without God's command to leave the body. So, too, it is ridiculous to hold that it is a service to God without God's command to forsake possessions, friends, wife, children.
God's commandment forbids the forsaking of wife and children.
...  Thirdly. In monastic vows chastity is promised. We have said above, however, concerning the marriage of priests, that the law of nature [or of God] in men cannot be removed by vows or enactments. And as all do not have the gift of continence, many because of weakness are unsuccessfully continent. Neither, indeed, can any vows or any enactments abolish the command of the Holy Ghost, 1 Cor. 7, 2: To avoid fornication, let every man have his own wife. Therefore this vow is not lawful in those who do not have the gift of continence, but who are polluted on account of weakness.
...  They cite also from 1 Tim. 5, 11ff concerning widows, who, as they served the Church, were supported at the public expense, where it is said: They will marry, having damnation, because  they have cast off their first faith. First, let us suppose that the Apostle is here speaking of vows [which, however, he is not doing]; still this passage will not favor monastic vows, which are made concerning godless services, and in this opinion, that they merit the remission of sins and justification. For Paul, with ringing voice, condemns all services, all laws, all works, if they are observed in order to merit the remission of sins, or that, on account of them, instead of through mercy on account of Christ, we obtain remission of sins. On this account the vows of widows, if there were any, must have been unlike monastic vows.
 Besides, if the adversaries do not cease to misapply the passage to vows, the prohibition that no widow be selected who is less than sixty years, 1 Tim. 5, 9, must be misapplied in the same way. Thus vows  made before this age will be of no account. But the Church did not yet know these vows. Therefore Paul condemns widows, not because they marry, for he commands the younger to marry; but because, when supported at the public expense, they became wanton, and thus cast off faith. He calls this first faith, clearly not in a monastic vow, but in Christianity (of their Baptism, their Christian duty, their Christianity]. And in this sense he understands faith in the same chapter, 5, 8: If any one provide not for his own, and specialty for those of his own house, he hath denied the faith.  For he speaks otherwise of faith than the sophists. He does not ascribe faith to those who have mortal sin. He, accordingly, says that those cast off faith who do not care for their relatives. And in the same way he says that wanton women cast off faith.