How you doing bro?
To partially answer your question...
The way I think of it is that Allah decides if islam is in your heart or not and although there are many non-believers who are the nicest people you will meet, being a muslims is paramount your five pillars of Islam are really really important (Zakaat, Prayer, Hajj, Declaration, Fasting).
Look at Abu Talib, he stood up for (his nephew) Muhammad(peace be upon him) until his old age and they went through many trials and tribulations together. He even moved away from his home during the boycott with Muhammad (PBUH) which lasted three years, but never actually made his declaration to islam and he loved Allahs messenger to bits.
The prophet peace be upon him asked him and asked him to declare islam and although Abu Talib believed Islam to be true he did not make his Shahadat -declaration to islam (There is only one god and Muhammad (peace be upon him) is his messenger). I think it was something to do with not wanting to dissapoint his father by changing faith or something. And the prophet may allah be pleased with asked him to change to islam, even in Abu Talib dying days. and he fought as hard as he could for islam Mashallah.
Only yesterday I was praying that Allah shows him mercy for the sake of the Prophet Peace be upon him. He was a good man and had a heart of gold, Inshallah allah will forgive him and grant him Jannah(Heaven) - I just wished he done his declaration.
There was such a beautiful story on this freeview channel I have (its called 'Peace TV' channel 820 on SKY, or watch online for free not matter where you live). By a scholar, called Hussain Ye.
Basically, may Allah forgive me if I am wrong at parts, but when he was a teenager he too was soul searching. But Mashallah Allah put islam in his heart and he decided to revert as a teen (19ish years old).
(In Islam when someone becomes a muslim, from being a non-muslim we call it reverting as we believe that all babies are born muslims, and so we are returning to back where we started)
Basically, the mother was very unhappy with this, I think she thought she lost her youngest son to islam (which she believed would separate them). But Masahallah he kept going back to his Mum and eventually she realised the beauty of islam and also reverted back to islam also:statisfie.
I know that does really answer your question, because I dot really know how to answer it properly tbh. But the way I look at it is like this -
Allah has put Islam in your heart, and while it may not be yet in your mothers, or your brothers, or your good friends or even those who passed away a non muslim. You can change that through talking to them about Islam. Or if they have passed away praying for them and putting it in All Mighty gods hadns. Allah is all forgiving and surely if All Mighty Allah wills he will forgive them and answer you prayers.
Hope that helps bro.
Btw, keep your eyes open for a guy called DR Zakir Naik, he is the guy that owns Peace TV. His islamic talks are AMAZING, he is all over Youtube if your interested.
PS I have attached a link of Hussain Yee talking about his reverting (if you are in a hurry for the part where he talks about his reverting then foward to 8mins in the video) the next part is in the 'Related videos' section (part 5), you can find the previous parts there also.
http://www.youtube.com/watch?v=uk7z8...eature=related
if the link fails type in google 'Hussain Yee - the Quran 4/5 youtube' or something. The reverting talk is at 8mins in part 4/5 and finishes in part 5/5.