The Lord spoke to Moses, saying, “Depart, go up from here, you and the people whom you have brought from the land of Egypt, to the land which I swore to Abraham, Isaac, and Jacob (Israel), saying, ‘To your descendants I will give it.’ I will send an Angel before you and I will drive out the Canaanite, the Amorite, the Hittite, the Perizzite, the Hivite, and the Jebusite. Go up to a land [of abundance] [d]flowing with milk and honey; for I will not go up in your midst, because you are a stiff-necked (stubborn, rebellious) people, and I might destroy you on the way.” – Exodus 33:1-3
This image of being “stiff-necked” conveys a spirit of rebelliousness, as J. A. Wharton (Interpreters Dictionary of the Bible, iPreach) describes:
A metaphor for rebellion and unteachableness, taken from the use of domestic animals for various kinds of work (#r[ “neck,” plus h`q “be hard” [in verb and noun forms]; sklhrotra”chlov). The ox “stiffens his neck” when he refuses direction, or “turns a stubborn shoulder” when offered the yoke (cf. Hos. 4:16; 10:11; Zech. 7:11-12; cf. Neh. 9:29). The term typically describes Israel’s rebelliousness against Yahweh during the wilderness wandering (Exod. 32:9; 33:3, 5; Deut. 9:13), which becomes a stereotype of apostasy (Jer. 7:26). Such rebellion consists in disobedience and idolatry (Exod. 32:9; Deut. 31:27), reversing the course of Yahweh’s redemptive history (Neh. 9:16-17; Jer. 7:26). A chief characteristic of the “stiff-necked” is refusal to listen to the word of God delivered through the prophets (II Kings 17:13-14; II Chr. 36:12-13; Jer. 7:25-26; 19:15; cf. Ezek. 3:7; Zech. 7:11-12), which in Acts 7:51-53 is called “resist[ing] the Holy Spirit” (cf. Isa. 63:10). God’s grace appears in sharp contrast to Israel’s stubbornness in Exod. 34:9; Deut. 9:6; II Chr. 30:8; Neh. 9:16 ff. The opposite of this attitude is the transformation of the external forms of the covenant relationship (see CIRCUMCISION; COVENANT) into a profound inner motive of obedience (Deut. 10:16), in willing submission to Yahweh’s will II Chr. 30:8).
Within the provisions of the Mosaic Covenant, there was really only one solution for sin—death. God was right in proposing the entire nation’s destruction to remedy their sin problem. Death was the only way that the Law could remove sin. And this is what the Law has done, only it is not we who have died for sin, but Christ. He died, under the curse of the Law, so that the problem of sin could be removed. He also rose from the dead, giving us a new covenant, and the power of the Holy Spirit, so that sin need no longer rule over us.
Not only are the Jews a stiff-necked people refusing to turn as the Lord instructs, so, too, are those people both heathen and those professing to be chosen of God and believing in Him and His Son become a stiff-necked people refusing the instruction and truth of the Lord our God.
We turn from God, Jesus the Lord, the Holy Spirit, and the life-giving reproving, instructing, inerrant word of God with our arrogance, our refusal to turn towards God and away from the trappings and entrapment of this world and its deceit and evil ways.
Today, a person may claim that their god is the Creator God, but if they are not obedient to the Creator God’s commandments, they are merely deluding themselves. Sincerity is only part of the picture. We are to worship in spirit and truth (John 4:24). The closer one’s associated with God’s work, the more necessary it is to make sure that the relationship with God is not marred by spiritual blemishes. Otherwise, the person cannot function properly as a channel for God to work through. God’s not glorified before the people unless His servants submit to His commands.
Apostasy is generally the fruit and effect of hypocrisy.