Without seeing the specific case I can only give a general answer. If I'm understanding your description, you are looking at an Ancestry index-only database such as the England, Select Births and Christenings, 1538-1975. Let's use that as an example.
Why do we write citations?
People commonly say that we need to cite our work so that we can find it again, or that someone else can use the citation to evaluate our work if there's a question or if we've made a mistake. Those things are true, but people overlook what I think is the most important consideration. Elizabeth Shown Mills says:
This screenshot was taken from page 10 of the 2nd edition of Elizabeth Shown Mills' Evidence Explained. In the current edition (3rd ed revised) it is on page 8.
If I wanted to post a "fastest gun in the west" answer, I could recommend that you get a copy of Elizabeth Shown Mills' Quicksheet for citing Ancestry databases (see link to newest edition in the reading list). I could also refer you to the discussions in the forum on the Evidence Explained website like this one from 2016: Ancestry citations where the problems of citing something from Ancestry are discussed.
But that doesn't address the core issue here, in that you are wanting to cite an index without evaluating what you're looking at.
The principle is to cite what you actually use. This discussion may be the most similar to your case: Multiple sources and records. The person asking is quoting indexes from several different websites. Elizabeth Shown Mills answered:
The bottom line is to cite what you use. In your discussion above, you
mention "indexes" but do not indicate whether you saw the certificates
you are citing. Does this FamilySearch or Ancestry database provide
image copies of those certificates, whereby you might confirm the
accuracy of the dates and glean other data? If you are using an online
derivative such as a database or index, rather than viewing an image
of the original, then your citation has to make that clear. The
typical way to do that is to cite what we actually use, then add that
our derivative source cites thus-and-such.
She goes on to advise her reader to consult section 2.11 of EE. She kindly points out that if we don't have EE or the Ancestry Quicksheet, that section of EE is available to read on the EE website under the "Sample Text Pages" tab. Section 2.12 is also part of that preview, and talks about the problems of citing a finding aid rather than consulting the original records.
You say that "the website data may actually be enough for my needs" but when you simply accept an extract at face value, you don't know the quality of the information. At the very least, I would suggest that you take the FHL film numbers provided by Ancestry and go to the FamilySearch catalog to read the catalog entry and the Film Notes for that film to get a better understanding of where the information came from.
It's important to remember, too, that sometimes the digital images and the indexes can be on different FHL microfilm rolls. Read the Film Notes and catalog information carefully. Learn how to do place searches, and check all possible jurisdictions.
Even if you can't view the image (perhaps because it is available only at a FHC or at the FHL), you can use that information in turn to learn more about the original that was indexed.
You can also look for alternative means of access. For example -- if the data came from a set of Bishop's Transcripts rather than a parish register, again assuming we're talking about England, are the parish registers available elsewhere? Has anyone published an independent transcription of the registers, either in book form (search in WorldCat, on the Internet Archive, etc.), on CD, or online? Is the parish included on FreeReg? Have you checked DustyDocs or UKBMD? Have you read the relevant article for the parish in the FamilySearch Research Wiki or on GENUKI?
Our goal should be to get to the original records, or as close to it as we can. If we rely on indexes only, we can't tell if the indexer has crammed a baptism date into a birth date field, or a burial date into a death date field.
It's especially concerning to me that you say you want to know how to cite this for an article. I agree with Elizabeth Shown Mills that you need to make it absolutely clear to your reader what you have looked at.
Further reading:
