an institution of the Lord by which he has promised to bless his faithful people and help them grow in grace
one of the four parerga, referring to ceremonies or rituals that make us aware of God's assistance. To believe such ceremonies can themselves make a person good is a religious illusion that leads to pseudo-service; but the same ceremonies can be an indirect service of God. Kant's four examples are prayer; church-going, baptism, and communion.
the gospel in God's Word and the sacraments. They are the vehicles the Holy Spirit uses to create or strengthen saving faith. Some deny the necessity of the means of grace for conversion. The Bible teaches that the Holy Spirit does not work faith apart from the gospel (read Romans 10:13-18).
The Means of Grace in Christian theology are those things (the means) through which God gives grace. Just what this grace entails is interpreted in various ways: generally speaking, some see it as God blessing humankind so as to sustain and empower the Christian life; others see it as forgiveness, life, and salvation.