I read a hadith that said Prophet Muhammad (PBUH) wanted to burn the houses of those who prayed at home. So this indicated that it is wajib to pray in congregation. I also read another hadith that said the salah of those who hear the azhan but does not come to the mosque will be invalid. But I live in a non-muslim country so there is no azhan here. So I usually pray at home. Will my salah be valid or not?
Ahadith advising us to pray at home
There are enough ahadith in which we are asked to offer some of our prayers at home:
The Hadith mentioned in this Post could be added to the above mentioned ones as it indicates that one even should pray at home! Why? because it compare's a house where people don't worship Allah with a grave and dhikr or reciting Quran is the easiest kind of worship, as one could do it anytime and anywhere!
Recommendation of Scholars
Scholars tend to say that it is better and recommended (mustahab, mandub) to pray at least (all) voluntary prayers at home!
Here a few clear evidences
A "marfu' hadith" - or maybe a saying of a Sahabi (May Allah be pleased with him)- from Muwatta' Malik which you may find in a longer Version in Sahih al-Bukahri an other Version in Sahih al-Bukahri said it was about night prayers in Ramadan, you may find the same hadith or statement in Sahih Muslim and Sunan abi Dawod.
And here is a commentary on the statement from al-Muwatta' in Arabic.
And here's a statement of ibn Qudamah from this article about voluntary prayers:
يقول الإمام ابن قدامة: "والتطوع في البيت أفضل؛ لأن الصلاة في البيت أقرب إلى الإخلاص، وأبعد من الرياء، وهو من عمل السر"
(My own translation take it with care!)
Offering the voluntary prayers at home is better, because the praying at home is nearer sincerity, and further from adulation and it's among the secret worships
I also read a long report of Sheikh Shuraim about Jumu'a prayer where he ends up that the Imam shouldn't do nafl prayer when finishing, and if he did he shouldn't pray more than two raka-a and leave two for praying them at home.
And finally a Fatwa from islamqa.
Comment on the Fatwa in OP and what to do in a non-Muslim country
Note that any of these scholars who are saying that it is wajib to pray at a mosque or in congregation -at the mosque- has lived his whole life in dar al Islam so their point of view is based on the assumption that those people who asked live in a Muslim society!
And some people forget that a prayer in congregation can be done at home at any place, while it would be preferable to do it in a mosque especially if you hear the adhan!
On the other hand you say you are not in a Muslim country so, then the question would be can you pray at a mosque? can you pray in congregation at home/office/work ...?
You should do your best to pray farz/fard prayers in congregation, if possible at a mosque! Among the prayers which are very recommended to be done at a Mosque there are especially the sobh (fajr fard/farz) and 'isha' prayer because of the Hadith you mentioned or this Hadith which you may find in Sahih al-Bukahri, Sahih Muslim and this longer version from Muwatta' Malik and other Sunnah Collections, you can also check some sayings of Sahabi in Muwatta' Malik here and here.
Whether your prayer would be valid and accepted by Allah or not (See here the answer of ibn 'Omar (May Allah be pleased with both of them) on a similar question)... it's not up to me to decide, but I would like to say that from a fiqh point of view any prayer which is done according to the ahkam of purity and prayer is valid, but of course a prayer in a mosque or in congregation would let you gain more thawab!
And Allah knows best!