First, believers become children of God. When we were baptized, a priest poured water on our heads and said, "I baptize you in the name of the Father, of the Son, and of the Holy Spirit." In the Old Testament, we read of Noah and his family, who survived the flood, a foreshadowing of baptism. The people of God crossed the river Jordan before they reached the land of Canaan, the image of eternal life and the everlasting covenant God promised. Similarly, we become part of God's family when we are baptized.
Second, "[The believers] come to share in the divine nature" (2 Peter 1:4), the new life in Christ. Paul writes, "Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death?...Just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life." (Romans 6:3-4) St. Paul clearly teaches that baptized believers enter into a mystical communion with Christ.
Finally, the believers become temples of the Holy Spirit, who sets their hearts ablaze with his fire so that they become holy. The call to holiness is the universal call for all vocations in Christ.
What a blessing baptism is! May all Christians give thanks to the loving Father for this gift, which grafts our lives like branches into the vine which is Christ. He makes us new members of his mystical Body which generously carries out his mission. "Go into the whole world and proclaim the gospel to every creature." (Mark 16:15)