When prayers are unanswered?

Roman Catholics do not read the Bible, only the Evangels (Gospels), so I suppose all this cannot apply to us.

Those are all very good reasons, backed up by God's Word. Let me give you a few more to consider from a book I have The Battle Plan for Prayer - In a chapter called What Are God's Answers to Prayer the author gives five answers God gives us. 1- Yes, immediately - It lines up with what God wants for you when you pray that specific prayer. 2- Yes, in due time - The timing for your prayer might not be quite right for God's yes, answer, but he will give you the desire of your heart when you are ready. 3- Yes, so you'll learn from it - Sometimes what we ask for isn't good for us, but we need to learn a lesson from getting what we ask for, so God gives us our request to show us his will. 4- No, because your heart's not right. Consider asking for a million dollars. What would you do with it? If your heart isn't right about what you ask for, you won't get it. 5- No, I've got a better plan. Sometimes it just seems that what we want has just got to be okay with God too, however, it's not. God knows the end from the beginning, so when what you think is best for you, doesn't work out, wait on God to give you the best solution for your situation. I love this book. For years I've been wanting to learn how to pray properly, with meaning and depth, and this book teaches you to do just that. If you've ever seen the movie War Room, this book is from the movie and gives you great guidelines to intensify your prayer life. I fully recommend it.

I find Isaiah 1:15-16 interesting.

People should never give up praying

Each bible version would likely be interpreted by a different source (= each church tends to use a different 'type' of the bible). Just a word changed here there, could slightly change the meaning of the verse. Re: when prayers are not answered, think of it this way (sorry, I can't quote the exact verses to you), think of a child asking the parent for a sharp knife. The parent refuses but gives the child something safer. The child cries and screams, 'but I like that shiny kitchen knife more'... I used that to explain to my kids (when they were little) of why I couldn't give them certain items. They were surprised but understood very well. NB. I did theology in the past. (Just in case you think I am too intelligent and managed to think of this all by myself .)

I just trust God to be fair all the time.