You can't get there from here to Eternity

One simple but significant error we Christians make in understanding “Eternity” is to assume that it is like Time, only it goes on forever and ever. A better understanding is that Eternity is outside of time, there is no time there, and as a result, it is more like everything happens at once. Our simple minds could not comprehend this apon our death and judgement without help from God, but by example, consider Satan and his dark angels. Satan made a decision, ‘in Eternity’, not to serve, so Satan’s decision is ‘for Eternity’. Fortunately for us, God has given us the gift of time, which is a way to prevent us from making a rash judgment that would have Eternal consequences – we are given time to repent before that happens.

Now consider God. God the Father begat God the Son, Jesus, in Eternity. God the Holy Spirit proceeds from God the Father (and God the Son for us non-Orthodox), and He proceeds in Eternity. So even though we time-based humans consider begetting and proceeding to be a sequence with a before and after, that simply is not the case in Eternity because there is no before and after in Eternity. Before and After are outside of Eternity.

This is why the Catholic Encyclopedia can say that the three persons of the Holy Trinity are “are co-eternal and co-equal: all alike are uncreated and omnipotent.” This is also why the Athanasian Creed has the words; "the Father is God, the Son is God, and the Holy Spirit is God, and yet there are not three Gods but one God." This is because begetting is an eternal generation, not a time-based generation.