I would like to hear your response on this. In general, there exist a set of behaviors that Christians consider sinful, though these behaviors may not be observed to harm anybody (even the person doing the behavior.)
Why might this be?
I am assuming that God is not simply making rules for the heck of it, but that there must be some consequence of some kind by which we may understand why such a behavior might be considered wrong or sinful.
The reason that something may be considered a sin primarily because it hurts your relationship with God. When God has ordered the world in a certain way, or decrees that certain things are not to His will, then going against it is a sin. A sin isn't something that is bad for others. It's bad for ourselves. So to judge something as sinful because it hurts others isn't going to get the full picture (though it certainly is one aspect of a sin, as we are also called to love others, by God).
However, there were certain laws that the Jews were told to keep in the Old Testament. As you mentioned Kosher dietary restrictions, I'll use that as an example. The Jewish people at the time were very much in danger of being annihilated by the various nations in the time. They were constantly at war, and they were nomadic, living simply off the land. God desired for them to flourish and prosper, and so certain laws were decreed that ultimately had the result of encouraging good health and hygiene. Kosher laws at the time were very useful in preventing food-born disease and healthy eating habits. Other things, like purification rituals, have a direct correlation to the modern guidance by our parents to wash our hands before we eat. You can imagine that at that time, it was even more important.
There are different kinds of decrees in the Bible. There are things considered outright sins, but also laws and regulations. Many of these (that aren't actually sins) were for certain peoples at certain times, but ultimately a sin is when we go against the will of God, through our own free will.
A good read here: http://www.newadvent.org/cathen/14004b.htm
Sin is not defined as such by any level of hurt caused to a human being. Sin is, in fact, "missing the mark"; the word has it's roots in the target-shooting of an archer - sin is, in effect, to miss the bulls-eye. First and foremost sin is any failure to live up to the perfect law of God, including all it's moral statutes. For the Jews, this included the social, moral and ceremonial statutes handed down from God through Moses.
Nowhere is it stated that sin is sin by man's measure; it's sin by God's measure.
Now, that being said, the old testament law was fulfilled in Christ, and he gave a new measure. It was one which was more about the heart than the head, and harder to live up to than simply following a bunch of regulations; it's a "law" of principled obedience:
12 So in everything, do to others what you would have them do to you, for this sums up the Law and the Prophets.
37 Jesus replied: “‘Love the Lord your God with all your heart and with all your soul and with all your mind.’ 38 This is the first and greatest commandment. 39 And the second is like it: ‘Love your neighbor as yourself.’
34 “A new command I give you: Love one another. As I have loved you, so you must love one another.
And this new code is a law of the Spirit:
4 So, my brothers and sisters, you also died to the law through the body of Christ, that you might belong to another, to him who was raised from the dead, in order that we might bear fruit for God. 5 For when we were in the realm of the flesh, the sinful passions aroused by the law were at work in us, so that we bore fruit for death. 6 But now, by dying to what once bound us, we have been released from the law so that we serve in the new way of the Spirit, and not in the old way of the written code.
So the question is: Does X show love, honor and respect for My God, my neighbor and myself? However, living this principle, this new law of love, is a thing in which we grow day by day and we are more conformed to the image of Christ.
The sidran's reply was nice, just more one point is:
1 Corinthians 10:11 KJV
Now all these things happened unto them for examples: and they are written for our admonition, upon whom the ends of the world are come.
Some commands are decreed as "a shadow of good things to come, and not the very image of the things" (Hebrews 10.1). Look at that verses:
Psalms 34:20 KJV
He keepeth all his bones: not one of them is broken.
Exodus 12:21,46 KJV
Then Moses called for all the elders of Israel, and said unto them, Draw out and take you a lamb according to your families, and kill the passover. (...) In one house shall it be eaten; thou shalt not carry forth ought of the flesh abroad out of the house; neither shall ye break a bone thereof.
"Huh?" (you think,) "What the problem with breaking a lamb's bones?". The answer comes in form of a prophecy accomplished, centuries later, when the perfect lamb is in the cross:
John 19:32-36 KJV
Then came the soldiers, and brake the legs of the first, and of the other which was crucified with him. But when they came to Jesus, and saw that he was dead already, they brake not his legs: But one of the soldiers with a spear pierced his side, and forthwith came there out blood and water. And he that saw it bare record, and his record is true: and he knoweth that he saith true, that ye might believe. For these things were done, that the scripture should be fulfilled, A bone of him shall not be broken.
Did you understand? "Don't break the lamb's bone" commandment is "non-harmful" but, God decreed it to Hebrews in form of prophecy. We learn to trust God in that kind of commandment, HE really KNOWS what he does! :)
I think too often we look at God's laws as things we shouldn't do to protect ourselves. Actually sometimes those things are there to bring us pleasure as well. For instance the Holy days and the sabbath. I think God understood that sometimes as people we need to stop what we are doing and take a moment to look at all the things that God has done for us. The Holy days and the sabbath were justo for that. Sometimes God's laws are not just chains, but often provide freedom in a different way.
