The passage
      v1. Paul has been speaking about the qualifications of those who minister in the church and has concluded with a summary of the gospel. He now examines teachings which are contrary to the gospel. In chapter 1, Paul made note of the false teachers operating in the church and now underlines the consequence of their ministry: believers are being led astray, having been sucked into their false teachings and moved away from faith in Christ. Jesus himself warned that in these last days believers would be deceived and led from a reliance on Christ, cf. Mk.13:22. The satanic origin of the false teachings serves to emphasize how dangerous they are.
      v2. The teachings, with their satanic origin, are proclaimed by teachers who have long lost the ability to discern God's truth (they have a "cauterized" conscience). So, they are a source of misinformation and this is evidenced by their failure to practice what they preach (they are marked by "hypocrisy").
      v3. Guthrie, in his commentary, captures the sense of this verse when he writes, "what was created for all men must therefore be legitimate for Christians." The extreme piety of the false teachers, reflected in their sexual abstinence and their adherence to the Levitical food laws (or possibly even vegetarianism), was for them a means of progressing their standing in the sight of God. Yet, such "righteousness" cannot transcend the righteousness that is already ours in Christ. The fact is, God's good creation is to be gratefully shared, enjoyed and appreciated. There is simply no value in abstinence for spiritual gain.
      v4. Paul now supports his case with a piece of basic theology which serves to legitimize a believer's full participation in life. Drawing on the creation narrative, Paul makes the point that "everything" created by God is "good". It is not right to suggest that some things (eg. sex, eating meat) are in themselves unholy. God's creation is good and is to be enjoyed. Yet, Paul sets out a condition, since he is not advocating hedonism. We must enjoy God's good creation within its design limits, eg. sex within marriage, eating meat that is not offered to idols. We are free to participate in all that we can give thanks to God for.
      v5. In this verse, Paul restates his teaching, rather than developing it further. A believer may properly participate in life (sex, eating meat, ...). God's creation is fit ("consecrated") for us because scripture tells us that it is good, but of course it must be thankfully enjoyed under God, rather than enjoyed without reference to God.

How free is free?
      Australians have a word that they use to describe someone who is joyless and judgmental. In Australian mythology, such people tended to be "churchies", that is, church members, affectionately described as "the women's police." The word used to identify these joyless people was "wowser". Interestingly, today wowserism is more a secular pursuit than a religious one. Secular wowsers are the anti this-and-that lobby, representing any number of protest groups, dedicated to opposing politically incorrect pastimes. When having fun these days it is very unwise to smile because a wowser will want whatever you are doing banned. C. J. Dennis defined a wowser as "an ineffably pious person who mistakes the world for a penitentiary and himself as the warder."
      It seems that Timothy was having problems with some wowsers in his congregation. They had obviously worked out a strict rule of behavior for the Christian life which involved, among other things, abstinence from sex and meat. There is always the temptation to think that some form of religious duty, some work of supererogation, a piety which exceeds even Biblical ethics, will somehow gain us favour before God, even progress our standing in his sight, but in truth, it is likely to do the opposite. A simple faith in Jesus earns God's total approval, but such a faith is easily eroded by legalism.
      In dealing with the problem, Paul reminds Timothy of a simple fact: the creation is good and is therefore, something we can rightly participate in and enjoy. Yet in confronting the wowsers, Paul doesn't give free reign to hedonism. The creation is to be enjoyed, but only in a way that respects the design limits. We are free to participate in everything that we can give thanks for, under God. Sex is good, but only within marriage, meat is good, but not meat offered to idols.
      So, in our passage for study we find guidance for handling the twin curses of legalism and libertarianism. In our own lives, as well as in the life of our church, we have all observed the pendulum swing between both extremes. When it comes to pietism, with its list of do's and don'ts, Paul sees it as little better than the "teachings of demons", serving to undermine the profound truth that salvation is by grace through faith and not of works. At the other extreme, libertines are reminded that freedom does not come without some constraints. We are not free to sin. If we can't look the Lord in the face and thank him for what we are about to do then we are probably not free to do it.

v2
      en + dat. "such teachings come through" - in. The preposition here probably takes an instrumental sense, ie. the teachings are mediated to the believers "by means of" the false teachers.
      uJpokrisei (iV ewV) dat. "hypocritical" - hypocrisy. The false teaching is hypocrisy in that it is applied hypocritically in the lives of the false teachers, ie. they don't do what they preach. In reality, they probably can't, as is always the case for a legalist. They are forced to pretend that they keep their do's and don'ts.
      yeudologwn (oV) "liars" - of those who don't speak the truth. Not so much "liars", rather, those who do not proclaim God's truth; they do not teach Biblical/gospel truth.
      kekausthriasmenwn (kausthriazw) perf. pas. part. "[whose consciences] have been seared as with a hot iron" - having been seared. Commentators opt for two possible interpretations: their consciences have been i] "cauterized" in the sense of losing sensitivity toward divine truth, or ii] "branded" in the sense that they now carry satan's brand, ie. they are owned by satan, "branded with the devil's sign", NEB. The first option is to be preferred.

v3
      kwluontwn (kwluw) pres. part. gen. "they forbid" - forbidding, hindering, preventing. The genitive agrees with "liars", indicating who is doing the forbidding. The false teachers are typical legalists, pietists. They have their package of rules and regulations for the Christian life which, presumably, they believe secures their standing in the sight of God and/or progresses their holiness. Of course, on numerous occasions Paul has countered this heresy with the simple truth that our eternal standing is by grace through faith and not works of the law. "Puritan" works of supererogation can take many different forms. The version promoted by these "legalists" was focused, at least in part, on an abstinence from sex and certain foods. This form of piety is also reflected in the problems addressed by Paul in his first letter to the church in Corinth, 1Cor.7. In fact, it is likely that these legalists align with "the circumcision group" in Galatians, "the weak" in Romans and are the same ones into "self abasement" in Colossians 2:8-23.
      gamein (gamew) inf. "to marry" - to enter into legal sexual relations. Sex is probably the issue here, not just the bond of marriage. It's very hard to be an ascetic, refraining from sex, when you are married.
      apecesqai (apecw) inf. mid. + gen. "and order them to abstain from [certain foods]" - to hold oneself away from. The "order them" is not in the Greek but is supplied for meaning. The grammatical form is a zeugma (that which is joined together) ie. the two infinitives (verbal nouns) "to marry" and "to abstain" are joined by the single participle (functioning as a verb) "they forbid", but it only properly suits "to marry" and therefore "order them" has been supplied by the NIV.
      brwmatwn (a atoV) gen. "certain foods" - foods. Given the use of this word in Romans and 1 Corinthians, it is likely that Paul intends the specialized meaning of "meat" to apply here. This is all about eating spiritually proper foods, particularly meats that are ritually clean, or possibly refraining from eating meat at all, ie. being vegetarian.
      aJ "which" - The antecedent, with which this relative pronoun agrees in number and person, is "foods", although "to marry" could also be an antecedent with which it would have a notional agreement.
      ektisen (ktizw) aor. "[God] created" - Christ's lifting of the food laws obviously drives Paul's argument, cf. "nothing is unclean in itself", Rom.14:14, Mk.7:19. Here Paul alludes to the creation, in that what God made is "good" and therefore, not to be rejected.
      eiV metalhmyin (iV ewV) "to be received" - for partaking. "To be gratefully shared in"
      meta eucaristiaV (a) "with thanksgiving" - A prepositional phrase commonly used by Paul, expressing gratitude for God's goodness.
      toiV pistoiV kai epegnwkosi thn alhqeian "those who believe and who know the truth" - by the believers and the ones having known the truth. The single definite article applies to both "those who believe" and "who know [the truth]" indicating that both are equally descriptives of the same entity, namely, Christians.

v4
      oJti "for" - because. The hoti clause provides the reason why it is ethically acceptable for believers to eat all foods (along with getting married and thus participating fully in life).
      pan ktisma (a) "everything" - every creature. The construction of the phrase, "all", followed by a noun without an article, serves to emphasize the individual elements of the "all". "Everything created"
      qeou (oV) gen. "God" - of God. The "every created thing" comes out of God, from God, and therefore by nature, is good. It is therefore, proper for a believer to participate fully in the rich diversity of life.
      lambanomenon (lambanw) pres. pas. part. "if it is received [with thanksgiving]" - take, receive. The participle serves to form an adverbial clause of condition. The believer is free to participate in life, but there is a condition, our participation must be "with thanksgiving." In a narrow sense, Paul may be referring to the prayer of thanksgiving performed prior to a meal, a prayer, that in a sense, sanctifies the meal. Yet, it is more likely that he is thinking in broad terms. We are free to participate in everything that we can give thanks for, under God. Paul is not advocating hedonism, but rather a participation in the "good" that God has given us to enjoy, eg. sex is good, but only within marriage, meat is good, but not meat offered to idols.