First off I am an American but i so Love Runrig. I am guessing about the meaning of the song. I don't know. But this is what it means to me so far.
I see Every River as a love song to the creator. Runrig has always been a band of Christians if not a Christian band. I'm writing the meaning in first person because that is how it's sung.
Four lines are all the ways we try to connect with our Lord in our time on earth.
People naturally believe in God. Something inside us just knows. When we try to deny him is when it gets complicated.
Now the years hold no fears, like the wind they pass over. Loved, forgiven, washed, saved
Pretty simple when you know that to die is to be with the Creator then growing old and dying isn't a scary thing at all. This is the best I can come up with so far. I would love to hear more thoughts.