In Exodus 6:6-8, God not only promised liberation from slavery, but also a land of their own in which they could be free. From the start, then, God’s promise had envisioned the completion of their deliverance. What he began in their deliverance, he would complete. (The New Testament later depicts our present experience along the lines of a new exodus: God has redeemed us through Jesus’s death at his first coming, and now we await our promised full inheritance at his return.)
But in 6:9, the Israelites didn’t believe these promises. This was because they had suffered so long, and they hadn’t yet seen the deliverance that Moses had already promised. So why should they trust the promise now? The answer is that God is trustworthy; but their hardships were so severe, and their most influential experiences with God so distant in the past, that they could not see past what they were experiencing.
Sometimes we don’t know why some promises take so long to fulfill; why did Israel suffer so long in slavery? Sometimes reasons for delay, including perhaps in our future inheritance, might lie with us (cf. Matt 24:14; Rom 11:25-26; 2 Pet 3:9, 12). Sometimes, however, they lie also in the fact that God is orchestrating matters on a wider scale. In the case of the exodus generation, the land that was going to be theirs belonged to somebody else; only after generations of mercy was God terminating the other peoples’ right to it (Gen 15:16). (See http://www.craigkeener.org/slaughtering-the-canaanites-part-i-limiting-factors/; http://www.craigkeener.org/slaughtering-the-canaanites-part-ii-switching-sides/; http://www.craigkeener.org/slaughtering-the-canaanites-part-iii-gods-ideal/.) Some complain that God is slow concerning his promises (2 Pet 3:4), when sometimes he is patient for the sake of delaying judgment (3:9).
Moses conveyed God’s promise to his people, but because of their suffering they did not listen (Exod 6:9). In today’s language, their hardship seemed to them more real than his promise. God does understand that hardships can break our spirits (cf. Prov 18:14; Mark 14:38; Luke 22:45), and he is near the brokenhearted (e.g., Ps 51:17; Matt 5:4). But Israel was starting on a path of unbelief and ingratitude in which they kept persisting even after seeing his signs that would deliver them. Eventually this would lead to discipline and would nearly lead to God abandoning them (e.g., Exod 32:10). At this point, however, he remains patient.
Often it’s hard for us to see far beyond our pain. God is faithful, however. As we often say in the Black Church, “God may not come when you want him to, but he’s always right on time.” God’s promises don’t always happen when we want them to. God’s blessings often don’t come the way we want them to. But God is worthy of our trust, and we can be sure that, in the end, he always has his people’s best interests at heart.
Please note: I reserve the right to delete comments that are offensive or off-topic.