How do we know the resurrection is guaranteed for believers?

Jesus explicitly indicates in John 6:54 that 'whoever eats my flesh and drinks my blood has eternal life, and I will raise him up on the last day.' This promise serves as a foundation for the believer's hope in resurrection. The act of eating and drinking symbolically represents the faith and acceptance of Christ's sacrifice and thus secures the believer's place in eternal life. Therefore, communion with Christ provides not only spiritual sustenance but also the assurance of resurrection on the day of judgment, which underlines the weight of believing in Him.