This type of Baptist church would be extremely conservative, such as an independent Baptist church or primitive (hard-rock or hard-shell) Baptist, rather than your run-of-the-mill Southern Baptist Church or Missionary Baptist Church. Sometimes churches that have beliefs like this also have other, very extreme, doctrine. Before you make a commitment to ANY church, do some research, read the Bible, ask other Christians that you respect, and check your own conscience. I'm not saying that it's wrong to have extremely conservative beliefs in some areas, because I have some conservative beliefs. Certain areas, such as watching TV, wearing certain clothes, drinking alcohol in moderation, playing cards, etc. are NOT specifically forbidden or encouraged in the Bible, however, but vary according to culture. However, some churches don't allow for differences in conscience in gray areas of scripture, and these churches sometimes tend to be rather controlling. In the end, a church should teach that we are saved by FAITH, and although we want to please the Lord and grow in sanctification, we're NOT going to be saved or damned on the basis of wearing pants or skirts.
Now, about the pants. This is a "gray area." Here are some of the arguments:
Argument: The Old Testament says that men and women shouldn't dress alike. (Deut 22:5) Pants (in western culture) are male garments, therefore women shouldn't wear pants.
Response: Christians are not under Old Testament rules. Also, in the Bible, men and women both wore robe-like garments anyway. NO ONE back then wore pants; in fact, men and women dressed in very similar clothes.
Argument: Pants are immodest because they show the shape of a woman's bottom, and thus encourage men to lust and sin. Therefore, Christian women should not wear pants.
Response: Pants DO show a woman's shape, but which is more immodest: a tight mini-skirt (or a skirt blowing up in the wind) or a pair of loose pants?
My response (as a conservative Christian woman, mom, AND as a fashion historian): Study the issue carefully and pray for guidance. Try to be modest (as the Holy Spirit directs you). Consider your part of the country and what you are doing; some areas and some situations (like church) demand stricter modesty than others. In any case, when you walk by, a man shouldn't break his neck looking at you, so don't wear things that are too tight, too low (in front), or too high of a skirt or "hooker heels." If you worry about a certain outfit, ask a serious, trustworthy guy you know, like your Dad, brother, or good male friend. They'll often tell you the truth. Don't try to attract attention to your "assets," and don't try to show off your wealth by wearing expensive clothes or jewelry. But you don't have to wear clothing that is so old-fashioned, dowdy, or unusual that you stand out (unless your conscience dictates to do so.) We know from early writing that the Christians did NOT stand out because of their clothing-styles. Try to be feminine, and wear colors that suit you, but that doesn't mean to be "frilly." Try to dress in such a way that a serious, down-to-earth man or woman would probably remember you more because of your kindness, intelligence, smile, or good attitude rather than what you were wearing.
This is my take on the issue. Check out the link below for a more thorough discussion of this issue.
In the interest of full disclosure, my mother was the first person in our little church to wear pants to Sunday night (no one would DREAM of wearing pants to morning worship at that time.) I don't remember it, but apparently she created quite a controversy at the time. I think it's rather funny myself, because I'm quite conservative.