Utimate objective of religion is success of the hereafter and in order to achieve success, tazkiya is required. This Tazkiya includes Tazkiya of body, Tazkiya of Meal and Tazkiya of ethics (Please see: Discussion 64226 • Reply 64263).When one adopts Tazkiya or strives to achieve it, then it also shows its results in this world, through formation of human beings who are at epitome of ethics and who form a scoiety based on high ethical values and this in turn makes a better society. Therefore, Islam is not totally cut off from this world, whatever is required by Islam for success in the hereafter, it actually has an impact on this world as well, if people start following it (Please see: Discussion 62861 • Reply 62930).
As far as attribution of Success and Failure to Allah is concerned, it is extension of our belief in Allah, that everything is under his control and is happening with his ‘izn‘ (Please see: Discussion 66226 • Reply 66264)