Does Acts 10:42 teach that a person must believe that Christ is to judge the living and dead in order to be saved?
In Acts 10 we read:
Peter declared to Cornelius that the apostles were ordered by Christ to preach that Jesus (i.e., the “One”), has been appointed by the Father to judge all the living and the dead.
To judge the living refers to the Judgment Seat of Christ, where Jesus will judge the believers (see 1Cor 3, 2Cor 5). Jesus will also judge the unsaved (i.e., the “dead”) at the Great White Throne Judgment following the Millennial Kingdom (see Rev 20). In this way, Peter meant that Jesus judges the living and the dead.
Peter's comment comes in a larger passage in Acts 10, where Peter was explaining his call to preach concerning Jesus to the world. Part of Peter's commission was to preach that Jesus would judge the world. Peter was not saying that every evangelist must include this detail in their presentation of the Gospel nor that every believer must accept this detail before being saved. He was merely explaining his personal commission as an apostle including teaching on this point, which Peter did in 2 Peter 3.