For lo! the days are hastening on
By prophet bards foretold,
When, with the ever circling years
Shall come the age of gold;
Is about the Hindu belief (Rig Veda) that history forms four ages that repeat over and over .I copid and pasted the following:-
The cycle of the four ages
Hindus believe that time goes in cycles and that each time period is a long one. Each cycle is called a yuga and there are four different yugas, each of which lasts for a different amount of time. At the end of each yuga, time is destroyed and then a new yuga begins. Hindus are currently in the age of Iron, and when it ends a new Gold age will begin.
YugaLength
Gold1,728,000 years
Silver1,296,000 years
Copper864,000 years
Iron432,000 years
The author of the hymn possibly did not know the Rig Veda is the origin of the phrase 'age of gold'.
I agree with Callistemon, and actually it does not matter where the phrase originated. As I said earlier, it's the feeling and the intention that matter. Anyway, Christianity is based on several older traditions such as Judaism, and Greek stoicism.