Amourbearer,
It is not a matter of Bible passages; it is the worldview of the Bible from beginning to end. It is the creationist worldview -- that our ethics are receptive rather than creative. We accept the world as God has created it, our lives as God has determined them, and our morals as God has revealed them. But if you need a specific text which sums up the creationist worldview I would point you to Romans 1:18-32. The need to distort and interfere with the natural order is ascribed to a perversion of the Creator-creature distinction and relation. Verses 26-27 emphasise the "natural use." If humans have the power to create their own world, to determine their own lives, to invent their own morality, then Romans 1 is false and we have no reason to place such emphasis on the righteousness of God which is by faith in Jesus Christ.
Actually, it does matter about Bible passages, because the Bible must interpret the creation account. We are creationists, but we interpret the creation account in a *Biblical* manner. For example, it would be silly to suggest that people should run around naked, or that we need to move over to the middle east, and work in a garden in southern Iraq. What is norminative in the creation account needs to be born out and interpreted by the scriptures themselves, and thus, the image of God needs to be interpreted by the scriptures.
In Romans 1, Paul is specifically addressing something the Bible addresses many times, and that is that God created male and female to go together, and thus, only those two genders can go together. This an interpretation of the creation account that is given elsewhere, even in the law [Leviticus 18:22; 20:13]. In this case, the Bible is interpreting the creation account. However, you will find no text of scripture that interprets the creation account in the way you do. Again, the creation account must be interpreted, and we must allow scripture to interpret it.
Not only that, but it is really simplistic to say that the Christian worldview is simply about creation and natural processes. It is also about dominion. We stop the natural process of the growing of trees to cut them down and use them for houses. We stop the natural processes of the growing of plants in order to eat them for food. What if we stopped the natural processes of having children in order to better serve God in some other way, such as helping at an orphanage, or working at a homeless shelter?
Not only that, sin is a reality. I don't think that can be brushed off as "a problem," as the reality is that we all have major "problems" so long as we live in this fallen world. A woman that has medical problems, and could die if she ever conceived is reason enough given the fall. Men who have never heard the gospel need to be told the gospel, and men who are going into gospel ministry need to be trained. All of this produces many tasks, and many areas of service that the church needs.
Combine all of these things with the fact that, as part of the Christian worldview, we are finite. We cannot do all of the things I just mentioned above. We have our limits. In fact, the book of Proverbs speaks of this:
Proverbs 25:16 Have you found honey? Eat only what you need, That you not have it in excess and vomit it.
God created honey to be good and desirable. Yet, we have to know our limits, otherwise we will get sick and vomit. That is why I say, it is way too simplistic to say that we believe in creation, and that God has created certain things to function in certain ways. He has, but we need to interpret the creation account in the way that the Bible does, and, within the Christian worldview, we are also called to take dominion of that creation, in a sin filled world, with all our limitations in order to serve God.
God Bless,
Adam