Because of original sin, we are born without grace in our souls, so there is no way for us to have fellowship with God. Jesus became man to bring us into union with his Father. He said no one can enter the kingdom of God unless he is first born of "water and the Spirit" (John 3:5)—this refers to baptism.
Through baptism we are born again, but this time on a spiritual level instead of a physical level. We are washed in the bath of rebirth (Titus 3:5). We are baptized into Christ’s death and therefore share in his Resurrection (Rom. 6:3–7). Baptism cleanses us of sins and brings the Holy Spirit and his grace into our souls (Acts 2:38, 22:16). And the apostle Peter is perhaps the most blunt of all: "Baptism now saves you" (1 Pet. 3:21). Baptism is the gateway into the Church.