How does universal redemption contradict the gospel?

Universal redemption posits that Christ died for every person, which ultimately undermines the gospel's central message of grace and the sovereignty of God in salvation. If Christ's death does not actually secure the salvation of anyone but merely makes it possible, then it places the responsibility of salvation upon the sinner’s faith instead of Christ's accomplished work. This contradicts the biblical portrayal of salvation, which is solely the work of God, where the efficacy of Christ's blood is not contingent upon human response but rather is a guarantee for His chosen people. As seen in Ephesians 5:25-26, the Scripture affirms that Christ gave Himself for the church, not universally for all mankind.