The sacraments are efficacious signs of grace, instituted by Christ and entrusted to the Church, by which divine life is dispensed to us."
[Catechism of the Catholic Church, 1131]
The word "sacrament" comes from the Latin word sacramentum used in Scripture to describe the mysteries of God. A sacrament is what brings the life of God into the human person - God doesn't just want us to believe in Him, He wants to live within us (John 15:1-11).
"Go and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit."
"If we acknowledge our sins, he is faithful and just and will forgive our sins and cleanse us from all wrongdoing."
[1 John 1:19]
"Whoever eats this bread will live forever; and the bread that I will give is my flesh for the life of the world."
"Then they laid their hands on them and they received the Holy Spirit."
"Husbands, love your wives, even as Christ loved the Church and handed himself over for her."
"And he gave some as apostles, others as prophets, others as evangelists, others as pastors and teachers, to equip the holy ones for the work of ministry, for building up the body of Christ."
OF THE SICK
"Is anyone among you sick? He should summon the presbyters of the church, and they should pray over him and anoint him with oil in the name of the Lord."