But you will say, How shall we know that this covenant belongeth to us? that we are such as we may say, God is our God?
I answer, first—to lay this for a ground—you must know that to be a God is a relation. Whosoever God is a God to, he persuadeth them by his Spirit that he is a God to. The same Spirit that persuadeth them that there is a God, that Spirit telleth them that God is their God, and works a qualification and disposition in them, as that they may know that they are in covenant with such a gracious God. The Spirit as it revealeth to them the love of God, and that he is theirs, so the Spirit enableth them to claim him for their God, to give up themselves to him as to their God.

Richard Sibbes, “The Faithful Covenanter” in The Complete Works of Richard Sibbes, ed. Alexander Balloch Grosart, vol. 6 (Edinburgh; London; Dublin: James Nichol; James Nisbet and Co.; W. Robertson, 1863), 8.

This is a profound bit of theology and needs some thought to be understood.

Consider first, “you must know that to be a God is a relation”. We too easily abstract God: God is a being with a set of attributes. Another sort of one has an idea of a celestial butler, the god of moral therapeutic deism:

As described by Smith and his team, Moralistic Therapeutic Deism consists of beliefs like these: 1. “A god exists who created and ordered the world and watches over human life on earth.” 2. “God wants people to be good, nice, and fair to each other, as taught in the Bible and by most world religions.” 3. “The central goal of life is to be happy and to feel good about ones self.” 4. “God does not need to be particularly involved in one’s life except when God is needed to resolve a problem.” 5. “Good people go to heaven when they die.” (As Dr. Mohler summarized Smith’s findings.)

Or some other god. But consider what Sibbes is saying: The “God” part of our understanding of God is relational. For instance, Moses speaks to Pharaoh of the “LORD our God.” There is a particular person(s) who is our God. Since He is God, we have a particular relationship toward him.

The abstract God is a powerful being, but we have little relationship to him. He have created us, but he may also have forgotten us: he is not God to us. The Therapeutic god is no God at all. He is a powerful helper, but he is not a God to anyone. That is why the Christian confession is that Christ is Lord.

The remainder of Sibbes’ discussion speaks about how God himself, God the Spirit, brings the human being into a right relation to God. God is there for everyone, but not everyone is God-worshipper relationship with God (indeed, one can think of sanctification as merely the process of turning human beings into right worshipers).

Whosoever God is a God to,
1) he persuadeth them by his Spirit that he is a God to.
2) The same Spirit that persuadeth them that there is a God,
3) that Spirit telleth them that God is their God,
4) and works a qualification and disposition in them,
5) as that they may know that they are in covenant with such a gracious God.
6) The Spirit as it revealeth to them the love of God, and that he is theirs,
7) so the Spirit enableth them to claim him for their God,
8) to give up themselves to him as to their God

Each of these elements makes plain what is in the relationship of “God”. There is a God. This God stands in some sort of relationship to the human being. The human being is in a covenantal relationship to this God. The human being’s affections, thoughts, dispositions, actions are brought into a correspondence to the covenant (that is also known as sanctification: note that sanctification is not merely morally appropriate behavior, although it is not less). Counseling/preaching is the process of using the Word of God (assisted by the Spirit of God) to bring about this relational process.