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.
RamakrishnaDifferent people call on [God] by different names: some as Allah, some as God, and others as Krishna, Siva, and Brahman. It is like the water in a lake. Some drink it at one place and call it 'jal', others at another place and call it 'pani', and still others at a third place and call it 'water'. The Hindus call it 'jal', the Christians 'water', and the Moslems 'pani'. But it is one and the same thing.
RamakrishnaDwell, O mind, within yourself; Enter no other's home. If you but seek there, you will find All you are searching for. God, the true Philosopher's Stone, Who answers every prayer, Lies hidden deep within your heart, The richest gem of all. How many pearls and precious stones Are scattered all about The outer court that lies before The chamber of your heart!
Ramakrishna