Some people use Galatians chapter 3 to say that we should not care too much about obeying God’s commands.  The passage that they use says the following:

1)  Gal. 3:1-5 - ¹You foolish Galatians! Who has bewitched you? Before your very eyes Jesus Christ was clearly portrayed as crucified. ²I would like to learn just one thing from you: Did you receive the Spirit by observing the law, or by believing what you heard? ³Are you so foolish? After beginning with the Spirit, are you now trying to attain your goal by human effort? ⁴Have you suffered so much for nothing—if it really was for nothing? ⁵Does God give you his Spirit and work miracles among you because you observe the law, or because you believe what you heard? (NIV)

If you are not familiar with the Bible, reading this passage out of context could portray this very idea—that we should not worry too much about resisting sin.  However, we must consider three things: 

(1)  What is "observing the law?"
(2)  What does it mean to                       "believe?" and
(3)  What is Paul referring to in              verse 3?

(1) In answer to this first question, whenever people in the New Testament (as well as the Old Testament) talk about “the law” it is almost always referring to the Law of Moses (the first five books of the Bible).  This is definitely the case in this passage, as seen by what Paul addresses throughout this book.  In Gal. Gal. 2:15-16, Gal. 3:1-5, Gal. 3:10-11, and Gal. 5:4, the Galatians were trying to be right with God by "observing the law."  So, what exactly were they doing?  Paul gives two examples.  One is circumcision (Gal. 2:3, 5:1-12, 6:11-15), and the other is "observing special days and months and seasons and years" (Gal. 4:10).  Both of these are ritualistic matters of the Old Testament law that we do not follow anymore (Gal. 3:25, Col. 2:16-17).  We follow Jesus Christ and what He taught (Rom. 7:6).  Furthermore, Paul says, “how is it that you are turning back to those weak and miserable principles? Do you wish to be enslaved by them all over again?” (4:9).  Would Paul refer to Jesus' commands as “weak and miserable principles”?  Surely not, because in 1 Cor. 7:19 he says, "Circumcision is nothing and uncircumcision is nothing.  Keeping God's commands is what counts."  "Observing the law" is also clearly defined in 3:10, which says, "All who rely on observing the law are under a curse, for it is written: 'Cursed is everyone who does not continue to do everything written in the Book of the Law.'"  By reading the beginning of Ch. 3 in its context, we can clearly see that Paul was condemning the Galatians' concern over keeping rituals from the Law of Moses, rather than condemning them for being concerned about obeying God's commandments.  Furthermore, if Paul were teaching in chapter 3 that we should not try to obey God, he would be utterly contradicting himself with these two statements that he later makes:

Gal. 5:19-21 - The acts of the sinful nature are obvious: sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions and envy; drunkenness, orgies, and the like. I warn you, as I did before, that those who live like this will not inherit the kingdom of God. 

Gal. 6:7-8 - Do not be deceived: God cannot be mocked. A man reaps what he sows. The one who sows to please his sinful nature, from that nature will reap destruction; the one who sows to please the Spirit, from the Spirit will reap eternal life.

(2) In reference to the message of Jesus, the meaning of the word "believe" is highly important.  It is how a man is saved, as seen in John 3:16, Acts 16:31, Rom. 3:22-24, and numerous other verses.  It is no light or small thing to believe in Christ, as many people make it out to be.  Jesus and his apostles portrayed believing as a whole-hearted commitment to follow him (as discussed in the Believe section).

(3) In Gal. 3:3, the NIV unfortunately translated the last word wrong.  In the KJV, a more accurate translation, this verse says, "Are ye so foolish? having begun in the Spirit, are ye now made perfect by the flesh?"  This underlined word, "flesh," is very different than the words that the NIV uses (human effort).  We can determine which word is correct by looking at the original Greek text for this passage.  The Greek word used is "sarx," which refers to either the body or the sinful nature.  It is possible that the word "flesh" could sometimes refer to "human effort," but only if the context clearly suggests it.  This, however, cannot be the case here for two reasons:  the Bible constantly tells us to make every effort to obey God and be holy (2 Pet. 3:14, Heb. 12:14-15, Luke 13:23-24), and we can understand the context of verse 3 by looking at how Paul uses the word "flesh" in other places within this letter to the Galatians.  The issue of whether or not they had to be circumcised in order to be saved is a central part of this letter.  Paul refers to circumcision using the word "flesh" twice in the KJV (Gal. 6:12 and 6:13).  It could make sense, then, that in verse 3 Paul is saying "having begun in the Spirit, are ye now made perfect by..." circumcision.  Also, Gal. 3:3 sounds very similar to Gal. 5:4, which is talking about circumcision:

Gal. 5:2-4 - ²Mark my words! I, Paul, tell you that if you let yourselves be circumcised, Christ will be of no value to you at all. ³Again I declare to every man who lets himself be circumcised that he is obligated to obey the whole law. ⁴You who are trying to be justified by law have been alienated from Christ; you have fallen away from grace.