When we Christians say the life of the Father and the Son is the Spirit we are not saying the Father is the Spirit or the Son is the Spirit, but that the 3rd Person is the actual life of the Father and the Son. What am I saying when I say the life of the Father and the Son? I am saying that life is a life that is uncreated, righteous, holy and uncreated as reflected in the Spirit. This is the life of the Spirit too, in fact for the Spirit is also spirit, just as the Father is spirit and the Son is spirit. God in all His complex is spirit. The Spirit is the life of the Father and the Son because the Spirit is the executor and renews creation, whereas the Son creates and the Father first speaks it forth in agreement of the council of the Godhead with the Son and the Spirit. And so it remains the distinction, coequal and coinherence of God's 3 Persons which never overlap. What is the life of the Father and the Son? The Spirit. What is the life of the Spirit? Eternality and Uncreatedness. It is very simple really. So too are the Father and Son eternal and uncreated. Father, Son and Spirit are One Being, not One Person. The latter is modalism, an ancient heresy. To be saved you don't have to be a rocket scientist in accepting the Trinity.