What did Paul mean when he said that we “should” walk in good works? Are good works optional for Christians?
I would say that good works are not optional for Christians. However, good works is something that comes natural to the Christian once they have received genuine salvation. While good works is not required for salvation, it is essential to a person’s salvation. As Martin Luther puts it in his book, The Freedom of a Christian, “Just as works do not make one believing, neither do they make one pious; but just as faith makes one pious, so it also makes one do good works.” According to 2 Corinthians 5:17, “Therefore, if anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new” (2 Cor 5:17, NKJV). If a person is saved, they will do good works because of their new desire to live for God and walk in His ways. Additionally, the Christian’s good works is proof of their faith. James says, “…faith by itself, if it is not accompanied by action, is dead” (Jas 2:17, NIV). Therefore, faith and good works go hand in hand and cannot be optional for Christians. Due to the two going hand in hand, a person may be able to determine that one serves the purpose for the other. In the case of faith and works, “good works are part of the purpose of our salvation”
According to David A. Croteau in Urban Legends of the New Testament 40 Common Misconceptions, the misunderstanding that works are optional for Christians stems from the use of the word “should” which provides an optional understanding of the verse. When the various translations of Ephesians 2:10 are examined it may appear that something different is being communicated through each verse. For example, the word “may” in the NET version communicates the idea of permission while the NIV’s translation says, “For us to do” communicating the idea of purpose. Either way, each version is attempting to communicate the idea of purpose, not through the verbs used in the middle of the sentence but through the first word in the phrase of each translation which includes, “so that, that and for”. “All those words at the beginning of the phrases are trying to communicate purpose.” It is also important to note that the works spoken of in Ephesians 2:10 doesn’t refer to any particular works that one may do but it refers to Christians walking in the ways of the LORD daily. Good works are not optional for believers because it is God’s purpose for saving us and for this reason, we will ultimately do good works.
 Martin Luther, The Freedom of a Christian(Indianapolis, Indiana: Hackett Publishing Company, Inc., 2013), 63
 David A. Croteau, Urban Legends of the New Testament 40 Common Misconceptions (Nashville, Tennessee: B&H Publishing Group, 2015), 146