What the apostle has in fact done in these introductory verses of the Epistle is to trace three stages of divine action for man's salvation. Stage 1 is the death of Christ for our sins to rescue us out of this present evil age. Stage 2 is the appointment of Paul as an apostle to bear witness to the Christ who thus died and rose again. Stage 3 is the gift to us who believe of the grace and peace which Christ won and Paul witnessed to.
At each of these three stages the Father and the Son have acted or continue to act together. The sin-bearing death of Jesus was both an act of self-sacrifice and according to the will of God the Father. The apostolic authority of Paul was 'through Jesus Christ and God the Father who raised him from the dead'. And the grace and peace which we enjoy as a result are also 'from God the Father and our Lord Jesus Christ'. How beautiful this is! Here is our God, the living God, the Father and the Son, at work in grace for our salvation. First, He achieved it in history at the cross. Next, He has announced it in Scripture through His chosen apostles. Thirdly, He bestows it in experience upon believers today. Each stage is indispensable. There could be no Christian experience today without the unique work of Christ on the cross, uniquely witnessed to by the apostles. Christianity is both a historical and an experimental religion. Indeed, one of its chief glories is this marriage between history and experience, between the past and the present. We must never attempt to divorce them. We cannot do without the work of Christ, nor can we do without the witness of Christ's apostles, if we want to enjoy Christ's grace and peace today.
Source: Stott, John (1968) The Message of Galatians (Leicester: IVP), p.19, here