Assalamo alikum brother.
What about those people to whom a message of the truth has not come
You mean people who who have NEVER heard about Islam? Allah will test them when they die, we're not sure how, but Allah knows, and of course, Allah is always just.
why do they suffer in this world.... also there are those to whom a message has not come and they have all the luxuries of this world
Suffer emotionally? if so, its because they feel like they are being deluded by the luxury of the world, they know it wont benefit them only for a short period of time, they want something to stay firm on for a long time, they know they'll not use it forever, so that makes them uncomfortable and need something spiritual in their life.
What is the purpose of their existance if no message comes to them
Well brother, we Muslims should spread the message of Islam to every possible corner in the world, and we were advised to do that, if we couldn't reach some certain parts of the world, then Allah will deal with it, because he knows why we couldn't spread the message of Islam in that specific place ( for example, the famous Indian island which is dwelled by really aggressive Indians, wont let you enter it, and they may kill you (literally) )
and where is the fairness that some of those people suffer in this world and some enjoy all the luxuries..???
Atheists always ask this too.
its because their leaders, presidents barely care about them, if they did care, they wouldn't stand it and they would quickly do something atleast, if I was a leader for example, I wouldn't let that happen in my country? I will find a way to stop this and find a solution so it doesn't happen.
We cant blame god here, we blame the leaders for their irresponsibility, they should be taking good care of the nation, not corrupting it, and what about others? we should be helping them and donating them too, so then Allah will ask us Why didn't you help them? so you need to be careful thinking about this brother.
And the others who enjoy the luxuries, shouldn't they be sharing their luxuries? , if I was a billionaire, I wouldn't lie and tell you 'I wouldn't have luxuries' I would, but I would share them too, because you have to make it fair, and when you do that Allah will reward you for donating your luxuries for those who don't have, and act justly towards humanity.
Such as people before Islam. Many people in the west today, to whom the clear message of Islam has not come, or even in some Muslim countries where people don't even know what Islam is....
Actually that's true, I've seen people ask about what is Islam, and so on, you see, there are some people who don't CARE about religion, they don't care about faith, they didn't question their existence, if they did, they would be looking for an answer, why are we here, and how? (which basically leads to finding a religion), and we have to try our best to spread the message of Islam throughout the world, if we couldn't (to some places where we cant reach or get to) then Allah will test them in his own way.
Some of these people live and die, without the message and still undergo suffering... some women burned alive, poverty, struggles, etc....
So if there is a God, why would he let these people live a life blindly without any message and purpose???
Because Allah doesn't change people's heart, if I want to change for example, I want to become a better person, then I will ask Allah for it, then he will change me inshallah, he will increase me in faith and health and strength, the Quran also talks about this ( I am not sure of the verse though i would like someone to point out the verse I'm talking about..)
Allah gave us free will too, to believe and disbelieve.
Al Quran Al Kareem (Surat Al Kahf, 18:29) "And say, "
The truth is from your Lord, so whoever wills - let him believe; and whoever wills - let him disbelieve." Indeed, We have prepared for the wrongdoers a fire whose walls will surround them. And if they call for relief, they will be relieved with water like murky oil, which scalds [their] faces. Wretched is the drink, and evil is the resting place."
So clearly as shown, Allah gave us free will to believe and disbelieve, it's just that, wither we want the truth or not, and wither we want to follow God's path or not, Allah has already sent the message.
Whereas for Muslims we understand suffering and it's purpose and how to deal with good and bad in this life.
Because we are following the true path to God, we understand God, and we know he is always with us, and as i explained, when we are on the right path to God, God will increase us in strength and faith, to understand him more.
Inshallah this answers your question.
Wa assalamo alikum, wa rahmtullahi wa barakato.