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.
RamakrishnaWith 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.
Ramakrishna