When people do not recognize the living God, it shows a lack of knowledge but also unwillingness, namely, the unwillingness to obey God. This is also evident in the case of Pharaoh.
What we see with Pharaoh is described by Paul in Romans 1:1–32:
Pharaoh does not know God, although God reveals himself in creation (Romans 1:20–21). Men have exchanged the majesty of the imperishable God for images of corruptible men, birds, walking and crawling animals (Romans 1:23); and in Egypt there were many gods who looked like man or animal or half-man half-animal.
Pharaoh refuses to obey God. With his iniquity, he violates the truth (Romans 1:18). God delivers him to his own sin (cf. Romans 1:28–31).
Pharaoh refuses to serve God and keeps others from doing so (Exodus 5:8). According to Romans 1:32 they rejoice that others do wrong too.
The fool says to himself, there is no God (Psalm 14:1–7 and Psalm 53:1–6). This means, God may exist, but he plays no part in my life. In Romans Paul applies this to all people (Romans 3:10–12). No man is righteous before God. But God declares us righteous through redemption through Jesus Christ (Romans 3:24). The deliverance from Egypt is a foretaste of this redemption.
1 Afterward Moses and Aaron went and said to Pharaoh, “Thus says the LORD, the God of Israel, ‘Let my people go, that they may hold a feast to me in the wilderness.’”