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.
With sincerity and earnestness one can realize God through all religions. The Vaishnavas will realize God, and so will the Saktas, the Vedantists, and the Brahmos. The Mussalmans and Christians will realize Him too. All will certainly realize God if they are earnest and sincere.
Spirituality automatically leads to humility. When a flower develops into a fruit, the petals drop off on its own. When one becomes spiritual, the ego vanishes gradually on its own. A tree laden with fruits always bends low. Humility is a sign of greatness.
It is not lust alone that one should be afraid of in the life of the world. There is also anger. Anger arises when obstacles are placed in the way of desire.
As for myself, I look upon all women as my Mother. This is a very pure attitude of mind. There is no risk or danger in it. To look upon a woman as one's sister is also not bad. But the other attitudes are very difficult and dangerous. It is almost impossible to keep to the purity of the ideal.
The sun can give heat and light to the whole world, but he cannot do so when the clouds shut out his rays. Similarly as long as egotism veils the heart, God cannot shine upon it.
All will surely realize God. All will be liberated. It may be that some get their meal in the morning, some at noon, and some in the evening; but none will go without food. All, without any exception, will certainly know their real Self.
When the head of a goat is severed from its body, the trunk struggles for some time, still showing signs of life. Similarly, though ahamkara (egotism) is slain in the perfect man, yet enough of its vitality is left to make him carry on the functions of physical life; but it is not sufficient to bind him again into the world.
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.
One man may read the Bhagavata by the light of a lamp, and another may commit a forgery by that very light; but the lamp is unaffected. The sun sheds its light on the wicked as well as on the virtuous.