Two passages in particular which are raised in objection to the practice of Lent, of fasting, and of abstaining from meat. The first is from Colossians 2:16:
Therefore let no one pass judgment on you in questions of food and drink or with regard to a festival or a new moon or a sabbath.The second is similar, from Galatians 4:8 - 11:
Formerly, when you did not know God, you were in bondage to beings that by nature are no gods; but now that you have come to know God, or rather to be known by God, how can you turn back again to the weak and beggarly elemental spirits, whose slaves you want to be once more? You observe days, and months, and seasons, and years!I am afraid I have labored over you in vain.We see here two primary points of contention. First, St. Paul would seem to be rejecting the notion that Christians ought to observe (in the Greek, literally, "celebrate") seasons or special days. Second, he says we should not be concerned about eating in a particular way. For good measure, we could add in 1 Timothy 4:3, which rejects the teachings of "liars" who "require abstinence from meats." What are we to make of this?
First, we can eliminate the concern that St. Paul really is rejecting the notion of observing particular days or seasons fairly easily by noting that Jesus Himself and the early Church observed them. Most notably, he observed the Passover - indeed He turned it into a uniquely Christian celebration, commanding that we "do this in memory" of Him. He also observed Hanukkah (see John 10:22 - 29). Once He had ascended into Heaven, the early Church also kept account of particular days. We see them meeting together for Pentecost in Acts chapter 2, and in Acts 20:6 - 7 we see that the disciples met on the Lord's Day (Sunday) to "break bread" - that is, to fulfill Christ's Passover command to "do this in memory of me."
The question of abstaining from meat and fasting is even clearer. Jesus Himself teaches that His followers "will fast" (emphasis mine) in Matthew 9:15. He famously gives instructions about not appearing disheveled "when you fast," indicating that it is not a question of if they should fast, but only of when and how. He tells us that some demons can only be driven out by fasting (Mark 9:29). The apostles themselves fasted on and around Pentecost - a "day" and season" - in Acts chapter 2.
As for abstinence, the New Testament authors provide instructions to abstain from meat for one reason or another in several places. The apostles issue a command to "abstain from meat offered to idols" in Acts 15:29. St. Paul offers counsel about circumstances in which it is good "not to eat meat" in Romans 14:21.
Of course, the commands about abstinence from meat are not universal, but are related only to particular circumstances, and this is in fact a key point in helping us to understand precisely what St. Paul means in the original passages in question. Clearly, it is acceptable that the apostles prohibit meat in certain circumstances, but it is never done as a universal rule. Moreover, there are no circumstances or qualifications attributed to those who St. Paul condemns in our citations above. What we might suspect here is a case wherein St. Paul's condemnation is of those who would prohibit the eating of meat as a universal rule.
In fact, there were two particular groups in the early Church who did just this. The Judaizers insisted that Christians must, in addition to following Jesus and His teachings, keep to every ceremonial law of the Jews, from circumcision to the prohibition against certain foods. This is understandable, given how important these practices were to the Jewish identity. The Lord even had to perform a miracle to finally convince St. Peter that it was acceptable to eat those foods that had previously been forbidden (see Acts 10). St. Paul spills a fair amount of ink in his epistles arguing against this early heresy, and the passages quoted above are examples of this. The other group in question is the gnostics, who believed that Jesus came to lead us to the purely spiritual and free us from all matter, which was taught to be evil. They therefore prohibited eating meat, getting married, and other such practices which they deemed to be too closely connected with matter and perpetuating it. St. John also argues against the gnostics in his epistles.
Fasting, abstaining from meat, and keeping particular days of celebration or reflection are entirely within the realm of sound Christian practice. Each of these was either expressly commanded by Jesus or the apostles, or was taught to us by the example of the early Church. This should be no surprise. Our human nature demands time of celebration and times of reflection. We work best as people who sometimes indulge, and other times deny ourselves. It's how we work, and the One who created us knows this well. He, through His Church, has given us the call to live in this way because He knows it is good for us. Thus, we observe Lent and we celebrate Easter. We set Sundays aside to give extra time to God. We pray particularly at night, before bed, and in the morning, before our days. We do these and countless other practices which help to keep us, in our human nature, walking with Christ. He made us this way, and if anything, we can be thankful that He has given us disciplines and practices which tie our humanity so closely to Him.