Short answer: This question should not be answered with a "yes" or a "no". It depends on how much God has revealed to you, and whether you are responding to His revealed word in faith.

Explanation

The topic of origins is very controversial, and there are very passionate people on "all sides" of the debate. However, I would suggest that at its roots, your question isn't so much about origins as it is about what makes a person a Christian, and how much freedom we have in our beliefs as Christians.

In an attempt to provide you with a useful answer (and avoid comment wars) I will generalize your question as follows: "Can I believe in -(insert doctrine here)- and still be a Christian?"

The Token Answer

Before providing a useful answer, I need to address "the token answer", which is "sure you can - lots of people do." The problem with this answer is that it assumes that because people do all sorts of things and call themselves Christians that it is ok to do all sorts of things and call yourself a Christian. I don't think this is a useful answer to any question of this form.

Defining "Christian"

There are many different "Christian" churches in the world, but what is "Christian" to one church may be "Anti-Christian" to another. If we just define Christian as "believing God is real", or "believing Jesus rose from the dead", then there aren't really any limits to what you can believe (after all, even the demons would fall into this category!) I will assume you are referring to the kind of "Christian" who is doing things right according to Scripture. From what I understand, a Christian would then be someone who has turned their life over to Christ and, is now (by necessity) walking by faith.

The Important Question

Biblical faith is not blind, is not based on the opinions of men, and is not based on our own understanding. It is a response to the word of God. So the important question is - "Has God revealed to you the truth about -(insert topic here)-, and if so, how have you chosen to respond?" So, it has less to do with what you believe, and more to do with how you are walking out your decision to live by faith (trusting the word of God.)

Illustration

For the sake of providing an origins-neutral illustration, let's say you're blind, and you are sitting in a chair in a room. Bob and Dan are in the room with you, and you have a sneaking suspicion that Jesus might be standing there as well. Your mom calls on the phone and asks you what color your chair is, but you're blind, so you don't know.

A) You could say "I don't know what color it is", and that would be a good, honest answer.

B) You could say "It's definitely blue, because I don't believe it would be red", but that would just be silly.

Now, suppose it was somewhat important that your mom know the actual color of the chair. You think to yourself "well, Jesus would be the most trustworthy person to ask, but I'm not sure if He's really standing there, and if I ask Him if He's there and it turns out that He's not, I'll look like an idiot to Bob and Dan. Even if it turns out that He is there, He may not answer me." So, you decide to ask Bob and Dan what color the chair is. Bob says it's black and Dan says it's green. But to be honest, you're not entirely sure that they aren't blind also. After thinking it over, you finally decide that in general, Bob is more trustworthy than Dan.

C) You could say "Bob says the chair is black, and I tend to believe him, but I can't say for certain", which would be a good, honest answer.

D) You could say "The chair is definitely black", but you might be on shaky ground with that answer, not knowing if Bob is blind or not, and not knowing if he is telling the truth or not.

Now, suppose that it is absolutely critical that you tell your mom exactly what color the chair is. In your desperation, you cry out to Jesus, asking Him if He is there. It turns out He is, so you ask Him what color the chair is. He says "the chair is yellow".

E) You could combine the answers from Jesus and Bob (considering them the two most reliable people in the room) and say "The chair is dark yellow - almost black", but you might be on shaky ground, because Jesus is perfectly trustworthy and that's not exactly what He said.

F) You could say "I believe the chair is yellow, because Jesus told me, and even though Bob and Dan are telling me something different, I trust the word of Jesus above the word of Bob and Dan". Of course, this would probably upset some folks... Bob and Dan might not like hearing that they are "blind", or "untrustworthy". But at least you would be pleasing your friend Jesus by demonstrating your trust in His word.

Things To Consider

How important is it to you to know the truth about this topic?

Who do you most trust to teach you the truth about this topic?

Have you asked God to reveal the truth to you about this topic?

Has He told you the answer?

Are you willing to believe Him even if people around you disagree?

Summary

You see, if God hasn't told you the truth about the matter, and you don't have any reason to believe that it is particularly important to Him, it would not be un-Christian to say "I tend to believe X, but I'm not certain", and leave it at that.

On the other hand, if you considered the truth of this topic to be of supreme importance, as a Christian it would only make sense to seek God for the truth. Once you have a clear word from God on the matter, it is our duty to trust what He says about it, despite the opinions of man.