What does Genesis 15:8 mean?
As the Lord's conversation with Abram continues, God reminds Abram of His promise to give to him and his descendants the land of Canaan. Now Abram asks for something tangible: "How can I know I will possess it?"Notice, as when he asked about having children (Genesis 15:2), Abram begins his question with great respect, addressing God as "O Lord God" or "Sovereign Lord." Abram's questions do not represent a lack of faith, accusation, or bitterness. This passage makes it clear that Abram has already put his faith in God (Genesis 15:6), and continues to do so. This is a request for God to reveal even more of Himself to Abram—Abram is asking for reassurance.
That's exactly what God will provide in the following verses. The symbolism of the ritual shown in these next verses is powerful, and includes prophetic hints at the future of Abram's nation. Along with this symbolism is a demonstration of how certain God's promise to Abram really is.