Salvation is attained in all the Four Ages through the Naam

Naam has been known and taught since very ancient times. It is God's own Law. Since the beginning of the world the Lord's Naam has been known to Saints and has been responsible for the salvation of mankind. Kabir Sahib, Guru Nanak and the other nine Gurus, Dadu Sahib, Paltu Sahib, Tulsi Sahib and many other Saints preached this Path to their disciples during the last centuries. The Mulsim holy men have taught the same Name during the last 1300-1400 years. Prophet Mohammed and other Muslim Saints like Shamas-i-Tabriz, Maulana Rumi, Hafiz and others also taught the Lord's Naam. St. John and Jesus Christ referred to the Lord's Naam some 1900 years ago. Similarly Zoroaster also taught it. Some two thousand five hundred years ago Mahatma Buddha practised the same Naam. Gorakh Nath also taught the same Naam. 

Archaeological excavations in Egypt show that King Ikhnaton, who ruled about 4000 years ago, encouraged its practice. Naam was then called 'Aton'. It was secretly practised in the time of the Upanishads, and there are many references to the Name, Naam in them. In the Copper Age, Lord Krishna was familiar with the practice of Naam. There are references relating to the practice of the Name in the Rig Veda, the oldest recognized religious book in the world. In its Vak Devi Sukt, the Naam is highly praised. 

Kabir Sahib said in his teachings that he came into the world in all the four ages, and that he preached the practice of Naam. He was known in the different Ages as Sat Sukrit, Maninder, Karunamai and Kabir respectively.

The Gurbani clearly mentions that people have been redeemed in all the four Ages by the Lord's Name.

In all the Four Ages, the highest thing is the Lord's Naam.

Gauri M3, 229-17

All creatures find release only through the Name, they attain to It by the Guru's Grace. 

 Bhairon M3, 1129-9

The Lord's Naam emancipates in all the Four Ages. It is through the Word that one deals in the Name.

 Sohle M3, 1055-1