The truth is that you cannot attain God if you have even a trace of desire. Subtle is the way of dharma. If you are trying to thread a needle, you will not succeed if the thread has even a slight fiber sticking out.
Only two kinds of people can attain self-knowledge: those who are not encumbered at all with learning, that is to say, whose minds are not over-crowded with thoughts borrowed from others; and those who, after studying all the scriptures and sciences, have come to realise that they know nothing.
The rishis of old attained the Knowledge of Brahman. One cannot have this so long as there is the slightest trace of worldliness. How hard the rishis laboured ! Early in the morning they would go away from the hermitage, and would spend the whole day in solitude, meditating on Brahman. At night they would return to the hermitage and eat a little fruit or roots. They kept their mind aloof from the objects of sight, hearing, touch, and other things of a worldly nature. Only thus did they realize Brahman as their own inner conciousness.
If you desire to be pure, have firm faith, and slowly go on with your devotional practices without wasting your energy in useless scriptural discussions and arguments. Your little brain will otherwise be muddled.
You speak of doing good to the world. Is the world such a small thing? And who are you, pray, to do good to the world? First realise God, see Him by means of spiritual discipline. If He imparts power you can do good to others; otherwise not.