Is it wrong to show a devout Christian (my friend) something that proves traditional Christian teachings are wrong ?

Does your friend try to tell you how to live your life based on their Christianity?  Do they think you are a bad person for not following the same religion?  Do they justify their own bad behavior using their Christian beliefs.  If "Yes", then it is completely appropriate to respond to them with evidence and examples of how Christianity is nonsense.  If "No", then leave them alone with their beliefs.

Most Christians welcome such "arguments" from those ignorant of God. It's like an invitation to share God's truth with them. Sounds like you can't "handle it", if you are afraid to even post what you believe to be true, for fear of getting exposed as ignorant.

No.

1Th 5:21 Prove all things, hold fast to that which is good.

This teaching even applies to the Bible itself.  If someone proved to me that the Bible was wrong, I'd have to go with the proof, and possibly even reject the Bible.  Truth is truth, and even the Bible is all about getting to the truth.

When we only hang around those who agree with us, there's little opportunity to see flaws in our beliefs.  A true Christian welcomes challenges that force them to dig deep to find answers.

1 Peter 3:15 But in your hearts revere Christ as Lord. Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect,

I'd love to hear your "proof".  You may be right.  There are many false teachings out there disguised as truth.

Faith tends to spiral upwards.  We go through phases of doubt and if we allow ourselves to doubt fully we may fall away or we may continue with stronger faith in the long run.  That said, there are many priests who have lost their faith and feel trapped because their friends, home and livelihood all depends on their faking that belief.  You don't want that to happen to her, and there are also more liberal options available if her doubts are about something like the virgin birth or the resurrection, where it isn't necessary to accept those things.  

You can try, but nothing proves it wrong.

No, all you do is annoy the friend. People do not react to religious arguments with logic but with emotion.

People have the freedom and the right to express their views and to disagree with others. One problem, though, is that very few people who claim to be Christians have a thorough grasp of what the Bible says, so if you can cherry pick proof texts to throw a spanner in her beliefs, that would be easy for you to do. Unfair, however. Are you prepared to wait until she's completed her ministerial course and has learned a great deal more? At the rate you're going, you will likely spoil your friendship as she will begin to see you as a submarine approaching her to launch a missile at her. But if she sees you as an iceberg, you couldn't blame her for giving you a wide berth!

There are lots of arguments people make against the Bible and Christian belief. I've come across no end of them over the last 40 years but those who have studied the Bible diligently and regularly are not phased by any of them. There's lots of literature around and web-sites too, dealing with the sort of attacks you will be making.  But until you are specific and state this one particular point that has upset her, nobody here can show you what might be wrong with your argument, so we can only take your word for it, that your Bible quotes are in context - which no sensible person would be prepared to do. Give us the Bible verses in question. Ask our views on them, and that way your Q couldn't possible get removed.

It's not wrong, but it's mean and insulting and probably pointless because religious folk know how to defend the Bible. They've been doing it for centuries. She'll probably drop you as a friend at some point.

Edit: It's obvious you are just an ATTENTION-SEEKER.  Don't bother to keep on updating if you won't say what you want us to help you with.  It's ridiculous talking in riddles.  Is that how you speak to your friend?  No wonder your friend is ticked off with you.

EDIT : I don't know why you are writing in riddles.  Why don't you just come out with what you mean? And what it is that you want to know?

Bible writers never claim that the message is their own examples -  (2 Samuel 23: 2 & 3)  (2 Timothy 3:16) (2 Peter 1: 19 -21) and (Jeremiah 30: 1 & 2)

What was it that you showed your devout Christian friend Liam, who is a trainee minister?  Was it 1 Timothy 2:12 by any chance?  Or 1 Corinthians 11: 3, 5 & 6 etc?  Or could it have been 1 Corinthians 14: 34 - 37?

That's what I don't understand about today's Church.  Either we follow ALL of the Word of God or none of it.  We cannot pick and choose but that is what many seem to do and I don't understand that myself, I have to be honest.

An atheist doesn't care about other people's religion. You should know that it's not worth it. Christians care so much because they think their god wants them to convert you. That's why they stick their nose in everything. To you none of it matters. Nobody wants you to convert anybody. Just sit back and relax.