Will they be saved who do not do good works?

Galatians 4:30
30 Nevertheless what saith the scripture? Cast out the bondwoman and her son: for the son of the bondwoman shall not be heir with the son of the freewoman.

From Jesse's blog:

Martin Luther's Commentary On Galatians 4:30

"And now they themselves do not defend their wicked life; nay, rather, they which are the best and the soundest of them all, do detest it; but they fight for the maintenance and defense of the doctrine of devils, for hypocrisy, and for the righteousness of works. Here they allege the authority of councils and the examples of holy fathers, whom they affirm to have been the authors of their holy orders and statutes. Therefore, we fight not against the manifest wickedness and abominations of the papacy, but against the greatest holiness and holiest saints thereof, which think they lead an angelic life, whilst they dream that they keep not only the commandments of God, but also the counsels of Christ, and do works of supererogation, and such as they are not bound to do. This, we say, is to labour in vain, except they take hold of that only and alone, which Christ saith is only necessary, and choose the good part with Mary, which shall not be taken from them.

Jesse quoted Luther, but simply quoted Luther's misunderstandings, or intentional twisting, of Catholic Doctrine.

First of all, as opposed to Luther's claim, the Catholic Church Teaches us not to judge ourselves.  This is from Scripture, which says:

1 Corinthians 4:3 But with me it is a very small thing that I should be judged of you, or of man's judgment: yea, I judge not mine own self.

And, again, as opposed to what Luther said, the Catholic Church teaches to follow the examples of Holy men who precede us in the Faith.  That is to say, to follow the example of the Saints which Luther maligns above:

1 Timothy 4:12 Let no man despise thy youth; but be thou an example of the believers, in word, in conversation, in charity, in spirit, in faith, in purity.

And the Church Teaches us to labour for righteousness sake.  Whereas, Luther claims that all labour is fruitless, as we can see above:

Proverbs 10:16 The labour of the righteous tendeth to life: the fruit of the wicked to sin.

Hebrews 6:10 For God is not unrighteous to forget your work and labour of love, which ye have shewed toward his name, in that ye have ministered to the saints, and do minister.

This did Bernard, a man so godly, so holy, and so chaste, that he is to be commended and preferred above them all. 

Here we see that Luther contradicts himself, acknowledging the holiness of the man which Catholics call, St. Bernard of Clairvaux.

He being once grievously sick, and having no hope of life, put not his trust in his single life, wherein he had lived most chastely; not in his good works and deeds of charity, whereof he had done many; but removed them far out of his sight, and, receiving the benefit of Christ by faith, he said: "I have lived wickedly. But thou, Lord Jesus Christ, by double right dost possess the kingdom of heaven: first, because thou art the Son of God; secondly, because thou hast purchased it by thy death and passion. The first thou keepest for thyself, by thy birth-right. The second thou givest to me, not by the right of my works, but by the right of of grace." 

Here, St. Bernard acknowledges that salvation is from Jesus Christ.  This is Catholic Teaching.

He set not against the wrath of God his monkery, nor his angelic life; but he took hold of that one thing which was necessary, and so was saved. 

Luther acknowledges that this is what St. Bernard teaches.  That salvation is by grace.  But does St. Bernard teach that salvation by grace is extended to those who do not do good works and reject the Commandments?  I'll answer that at the end of the article.

I think that Hierome, Gregory, and many other of the fathers, were saved after the same sort. And it is not to be doubted but that also, in the Old Testament, many kings of Israel and other idolaters were saved in like manner, who, at the hour of death, casting away their vain trust which they had in idols, took hold of the promise of God, which was made unto the seed of Abraham, that is to say, Christ, in whom all nations should be blessed. 

Note that Luther here, extends salvation to idolaters by the criteria of his own opinion.  Notwithstanding, the Catholic Church Teaches that God alone judges salvation.

Hebrews 12:23 To the general assembly and church of the firstborn, which are written in heaven, and to God the Judge of all, and to the spirits of just men made perfect,

And if there be any of the papists which shall be saved, they must simply lean not to their own good deeds and deserts, but to the mercy of God offered unto us in Christ, and say with Paul: "I have not mine own righteousness which is of the law, but that which is by faith in Christ," (Phil. iii. 9.)" (Excerpt taken from "A commentary on Saint Paul's Epistle to the Galatians")