Almost since the beginning of time, we have wondered, pondered, contemplated, argued, and fought over this one question; "If God is good, loving, and merciful, why does He allow suffering and pain?". The short answer is, 'He doesn't, you do'!
See... suffering is actually a tool that is intended for you specifically, not the world populous in general. Sort of a separating of the sheep from the goats, as we recently discussed. Too often, we want to lump the world (the masses) into an individual issue/problem... a sort of 'group therapy' approach to solving a problem, or at least a "it's not me, it's them" deflection technique. At the core though, God desires a closer, deeper and more trusting relationship with you, not your neighborhood, not your city/town, not your 'clan' or family... you personally. Sure, this will pour over to them, but it all begins with you at the center. You and Him.
Now, why you even HAVE problems, sorrow, turmoil, anguish, heartache, and a seemingly endless list of chaos in your life... is even easier to explain. See, James 1:2-4 states; "My brethren, count it all joy when ye fall into divers temptations; (3) Knowing this, that the trying of your faith worketh patience. (4) But let patience have her perfect work, that ye may be perfect and entire, wanting nothing.", which is to say... He cares deeply for you, but you must learn to trust, to have faith, and certainly to have patience and 'accept' His challenge for growth... and not 'cop-out' with the "Why does God let the world suffer" generalization.
The core meaning and purpose for suffering is to awaken our sleeping souls to His leading, to His nurturing hand in our lives. There are some who see that hand as mean, angry, even hateful (separating the sheep from the goats, again)... and rather than consider that 'they' are at fault or that He IS reaching out to touch you/them, it seems so much easier to criticize, to judge His ways, even to fight against it. Conveniently making it NOT their fault, and keeping it from being a personal thing, where suffering really impacts us.
If all things were pleasant and simple, everyone should/would have a close relationship with the Lord... but, that verse 3 actually starts by reminding us that we can 'count it all joy'. Not that suffering IS joyous... on the contrary, it hurts, it causes stumbling, faltering, pain, questioning and anguish... but, it is a clear and loving path to a deeper fellowship with the Lord. When you approach your suffering with hopeful anticipation for the 'glory outcome' in the Lord, you have taken a very keen step toward following His leading, and not whining/moaning about it... no longer blaming God for 'the worlds suffering', but accepting the challenge if your suffering.
Why?
Psalms 107:21-22 Explains it as; "Oh that men would praise the Lord for his goodness, and for his wonderful works to the children of men! (22) And let them sacrifice the sacrifices of thanksgiving, and declare his works with rejoicing." That is to say that not all your suffering is FOR you... it may be for an example for those around you (that whining world) to see 'first-hand' that He does love us, He does care, He does have a Meaning of Suffering!