Abraham and the smoking fire pot
Abraham. He fascinates me. I'm not alone. He fascinates a billion Muslims, and another billion Jews and Christians. Why is it that three major religions claim Abraham as a (or perhaps the) father of their faith? One way to look at is that God made good on his promise to Abraham. He has become father of so many they can't be counted. When God speaks directly to a person, we tend to deify that person, but Abraham was terrified, like you and I would be, when God spoke to him.
God: "Look up at the heavens and count the stars"--then God appears to needle or nearly joke with the then named Abram--"if indeed you are even capable to count them." The point seems to be that his offspring will be beyond counting.
The covenant that God makes with Abraham is vital to begin understanding why he is so important to Jews and Christians. I don't understand enough about Islam to know what connections they make to him.
Paul repeats in Romans 4 what comes next, also an aside in the Genesis 15 account: "Abram believed the Lord, and he credited it to him as righteousness." God talks about the land next: "I am the God who brought you out of Ur to give you land." So here is the summary: God promises a nomadic childless elderly couple land and more children than they could ever imagine.
Still, Abram is unsure: "How will I know?"
Now Abram does the only action in the story besides talk: he obeys God and brings a cow, goat, and ram. He cuts each in half (he also brought birds but didn't cut them in half). He does something else in the story, he chases off buzzards then walks through the halves of the animals. Why does he walk through the halves? That's an ancient way to make and keep a vow: sometimes the participant would say something like, "may I be diced the same way if I break this covenant."
That's the end of Abram's action. God is the one acting in this story. He puts Abram into a trance and a depression or darkness descended on him. God said these offspring he'd promised would be enslaved yet God would rescue them. He assured Abram he would live to a respectable age then be buried in peace. His descendants would return to this land after an exile in Egypt.
A smoking blazing pot then passed between the pieces of carcass, symbolizing perhaps a blessing of the great land (essentially the area of Solomon's eventual kingdom), that Abraham's nomad (essentially the original meaning of Hebrew, wanderer) would possess.
And on that day, God made this covenant with Abraham. The faith has wandered far and wide, an ever expanding universe of God's desire and renown and glory. Who really knows the mysteries of God's ways?