He commissioned us to preach to the people and testify that he is the one appointed by God as judge of the living and the dead.
For this apostolic teaching to flower, the hearers must believe in
the existence of God
God's personal interest in human beings
the possibility of being among the living in the afterlife
the possibility of being among the dead in the afterlife
God's plan to appoint a judge of the living and the dead
God's intention to appoint a judge of the living and the dead
Only with faith in these tenets does it make sense to believe that
Jesus is the one appointed by God as judge of the living and the dead
In practice, many Christians -- going back to the Syro-Phoenician woman and the man born blind, among others -- first profess faith in Jesus and only later understand and accept all that God has revealed of His plan for our salvation. But as a logical matter, if you don't accept the first seven points above, accepting the last point would be meaningless.
Which raises some questions. How many of those to whom Christians are commissioned to preach the Gospel accept all, or even any, of the first seven points? For that matter, how many Christians accept them all?
You won't get far preaching a Savior to people who don't know they need one.