From John Frame in The Doctrine of the Knowledge of God:
Knowledge subject to God's authority. In Scripture knowledge is very closely linked with righteousness and holiness (cf. Eph. 4:24; Col. 3:10). These "go together" (1 Cor. 8:1-3; 1 John 4:7f.). Knowledge of God, in the fullest sense, is inevitably an obedient knowledge. Let me sketch five important relations between knowledge and obedience.
1. Knowledge of God produces obedience (John 17:26; 2 Peter 1:3, 5; 2:18-20). God's friends necessarily seek to obey Him (John 14:15, 21; etc.), and the better they know Him, the more obedient they become. Such a relation to God is inevitably a sanctifying experience; being near Him transforms us, as the biblical pictures of God's glory being transferred to His people, of His Spirit descending on them, and of their being conformed to His image indicate.
2. Obedience to God leads to knowledge (John 7:17; Eph. 3:17-19; 2 Tim. 2:25f.; 1 John 3:16; cf. Ps. 111:10; Prov. 1:7; 15:33; Isa. 33:6). This is the converse of the previous point; there is a "circular" relation between knowledge and obedience in Scripture. Neither is unilaterally prior to the other, either temporally or causally. They are inseparable and simultaneous. Each enriches the other (cf. 2 Peter 1:5f.). In my view, some Reformed "intellectualists" (Gordon Clark has applied this label to himself) have failed to do justice to this circularity. Even in the writings of J. Gresham Machen, one often finds the slogan "life is built upon doctrine" used in a way that distorts the fact that in some senses the opposite is also true. It is certainly true that if you want to obey God more completely, you must get to know Him; but it is also true that if you want to know God better, you must seek to obey Him more perfectly." [The circle goes even farther: knowledge originates in God's grace and leads to more grace (Exod. 33:13), which leads to more knowledge. In this case, however, there is a "unilateral" beginning. Grace originates knowledge, not vice versa.]
This emphasis does not contradict our earlier point that knowledge is by grace. Knowledge and obedience are given to us simultaneously by God on the basis of Jesus' sacrifice. Once they are given, God continues to give them in greater and greater fullness. But He uses means; He uses our obedience as a means of giving us knowledge, and vice versa.
3. Obedience is knowledge, and knowledge is obedience. Very often in Scripture, obedience and knowledge are used as near synonyms, either by being set in apposition to one another (e.g., Hos. 6:6) or by being used to define one another (e.g., Jer. 22:16). Occasionally, too, knowledge appears as one term in a general list of distinctly ethical categories (e.g., Hos. 4:lf.) and so is presented as a form of obedience (cf. Jer. 31:31f.; John 8:55 [note the context, esp. vv. 19, 32, 41]; 1 Cor. 2:6 [cf. vv. 13-15; "mature" here is an ethical-religious quality]; Eph. 4:13; Phil. 3:8-11; 2 Thess. 1:8f.; 2 Peter 1:5; 2:20f.). In these passages, obedience is not merely a consequence of knowledge but a constitutive aspect of it. Without obedience there is no knowledge, and vice versa.
The point here is not that obedience and knowledge are synonymous terms, interchangeable in all contexts. They do differ. Knowledge designates the friendship between ourselves and God (see below), and obedience designates our activity within that relation. But these two ideas are so inseparable from one another that often they can legitimately be used as synonyms, each describing the other from a particular perspective.
4. Thus obedience is the criterion of knowledge. To determine if someone knows God, we do not merely give him a written exam; we examine his life. Atheism in Scripture is a practical, not merely a theoretical, position; denying God is seen in the corruption of one's life (Pss. 10:4ff.; 14:1-7; 53). Similarly, the test of Christian faith or knowledge is a holy life (Matt. 7:21ff.; Luke 8:21; John 8:47; 14:15, 21, 23f.; 15:7, 10, 14; 17:6, 17; 1 John 2:3-5; 4:7; 5:2f.; 2 John 6f.; Rev. 12:17; 14:12). The ultimate reason for that is that God is the real, living, and true God, not an abstraction concerning whom we can only theorize, but one who is profoundly involved with each of our lives. The very "I am" of Yahweh indicates His presence. As Francis Schaeffer says, He is "the God who is there." Thus our involvement with Him is a practical involvement, an involvement with Him not only in our theoretical activity but in all of life. To disobey is to be culpably ignorant of God's involvement in our lives. So disobedience involves ignorance and obedience involves knowledge.
5. Therefore it is clear that knowledge itself must be sought in an obedient way. There are commandments in Scripture that bear very directly on how we are to seek knowledge, that identify the differences between true and false knowledge. In this connection, we should meditate on 1 Corinthians 1-2; 3:18-23; 8:1-3; and James 3:13-18. When we seek to know God obediently, we assume the fundamental point that Christian knowledge is a knowledge under authority, that our quest for knowledge is not autonomous but subject to Scripture. And if that is true, it follows that the truth (and to some extent the content) of Scripture must be regarded as the most certain knowledge that we have. If this knowledge is to be the criterion for all other knowledge, if it is to govern our acceptance or rejection of other propositions, then there is no proposition that can call it into question. Thus when we know God, we know Him more certainly, more surely than we know anything else. When He speaks to us, our understanding of His Word must govern our understanding of everything else. This is a difficult point because, after all, our understanding of Scripture is fallible and may sometimes need to be corrected. But those corrections may be made only on the basis of a deeper understanding of Scripture, not on the basis of some other kind of knowledge.