When I was younger, the acronym “ACTS” was a popular shorthand for helping people to remember how to pray. The four letters stand for: Adoration; Confession; Thanksgiving; Supplication. We begin with God, and move on to sin, the solution for sin, and intercession for others.
In a similar vein, John Calvin believes that all Christian duty–non just prayer, but all Christian service of the divine majesty, all Christian thinking about how the creature relates to the Creator–can be subsumed under four heads: Adoration, Trust, Invocation, and Thanksgiving. He sketches this in Institutes 2.8.16 under his discussion of the First Commandment. All four direct man to his proper end and the source of all his blessings, which is God himself, who is to be received, rested upon, and obeyed in all things, and to whose Law and will our consciences and our entire selves are to be brought into subjection.
The duties which we owe to God are innumerable, but they seem to admit of being not improperly reduced to four heads: Adoration, with its accessory spiritual submission of conscience, Trust, Invocation, Thanksgiving. By Adoration, I mean the veneration and worship which we render to him when we do homage to his majesty; and hence I make part of it to consist in bringing our consciences into subjection to his Law. Trust, is secure resting in him under a recognition of his perfections, when, ascribing to him all power, wisdom, justice, goodness, and truth, we consider ourselves happy in having been brought into intercourse with him. Invocation, may be defined the retaking of ourselves to his promised aid as the only resource in every case of need. Thanksgiving, is the gratitude which ascribes to him the praise of all our blessings. As the Lord does not allow these to be derived from any other quarter, so he demands that they shall be referred entirely to himself.
