Conversion is the decisive passage from self-ruled life in Adam into surrendered life in Christ, when the sinner turns to Christ in repentant faith and the Spirit joins him to the risen Son.
Conversion is one turn with two aspects: repentance, the turning from self-rule, and faith, the entrusting of oneself to Christ. In that turning the Spirit gives life by joining the believer to the risen Son.
Conversion, regeneration, and union are not three separate transactions on an assembly line but one saving reality seen from distinct angles. The sinner believes, and the Spirit gives life; faith does not regenerate, and the Spirit does not believe. The two meet in the moment a person passes from death to life.
See in Scripture: Mark 1:15; Acts 3:19; Acts 20:21; Romans 6:3–11; 1 Thessalonians 1:9