Short answer: No, it's not valid to ask whether Christianity teaches X because Christianity as you're imagining it, doesn't exist. You're looking at Christianity as a single entity.
In logical terms, this is what's known as a "category mistake".
To clarify, using examples:
It would be valid to ask:
- "What does David Stratton say about X?".
- "What does Affable Geek say about X?"
It's valid because there is a definite belief that either of us has about any given topic.
Likewise, it's valid to ask the following:
- "What does the Roman catholic Church teach about X?"
- "What does the LDS Church teach about X?"
Both of those institutions have a definite structure, and a strict level of orthodoxy. There is an ultimate (earthly) authority behind each that is looked to as canon when applying an understanding of Heavenly teachings.
We start to get into grey areas with:
- "What do Baptists teach about X?
- "What do Creationists say about X?"
- "What do Mormons teach about X?"
Now we're getting into groups that don't have a central (earthly) authority, and much of what each group teaches varies based on personal opinion. There's no pope, and no President of the Church or Quorum of the Twelve to give an official statement.
Take a look, specifically, at the last example in the last group - "What do Mormons teach?" and compare it to "What does the LDS Church teach?" can you see the difference? For the LDS Church, there is an official Church position. For what Mormons teach, it is very possible that different members of the LDS Church understand some things differently and might not teach exactly what the official Church teaching is.
(OK maybe that's not likely, but it is likely that, where there is no official Church position, teachings may vary.)
So we come to "What does Christianity teach about X?" and the category mistake.
"Christianity" is not one single institution. Christianity is made up of the body of all believers1 who have ever existed. This includes the Apostle Paul, Kent Hovind, Pope John Paul, Charles Finney, Joseph Smith, Billy Graham, my Mom, me, and countless others.
As you should be able to see from the above, there's a scale between what can be considered official teachings and personal opinions. you should already be able to see that "What does is the official LDS position on X?" is vastly different than "What do members of the LDS Church believe about X?"
I can guarantee you that even if you eliminate everyone else there is disagreement between my Mom and me. from that point alone it's not valid to ask "What does Christianity say about _______?" because even if you include just the two of us, you're going to get the same answer on some subjects, and different answers on others.
Fill in all of the multitude of Christians that have ever existed and you can see that it's impossible to answer any question about "what Christianity teaches".
So, if your question has been closed, but you still hope to get an answer, what are your next steps?
Now, with all of that said, I hope you don't get discouraged. Even though there is a vast array of beliefs within Christianity, there is also a remarkable unity on may points. If you're here because your question has been closed, there may be a way to get the question re-opened and get your answer. You'll just need to put in a little effort and decide whose opinion you value. Do you want a Catholic perspective? Perfect! You should be able to scope your question that way.
If you have no clue how to edit your question to make it suitable for re-opening, try the tips found here.
If you're still stuck, put a comment on your own question asking for help. Most of us really do want to be helpful, and if you've taken the time to read this long-winded post, and leave a comment asking for help, it's quite likely that one of us will try to help you out.
1 The definition of believers here is "those who consider themselves to be Christians". (You may not consider them all to be Christians / believers.)