How are modern day Christians related to Abraham in the Bible? something about a spritual seed?

Answer 1

In the scriptures Abraham is a picture of God the Father and Isaac is a picture of Jesus Christ. Please read Genesis 22 which shows a portrait of the cross and the blessing that follows. From Abraham we have the nation of Israel, God's chosen nation in the Old Testament.
This reflects a spiritual truth in that those who come to faith in Christ are born from the seed of Abraham (God the Father).
Hence we have the term "born again Christian".
Since Jesus came and died for our sins, this historical event allows God to multiply his believers over the face of the entire world and God leads them to their true promised land... heaven itself. God's true chosen people are the spirtual nation of Israel, those whose sins have been washed by the blood of Christ.

Answer 2

It has to do with the Promise God made to Abraham that through his seed (Isaac) all the world would be blessed.
That happened when Jesus appeared.
The promise was never to Jews only, but always to all the nations of the world. We (gentiles) are adopted into Abraham's family by our faith, as Abraham had faith and it was counted to him as righteousness.
I hope that wasn't too complicated for you. It was for me, for a long time. I had to work on it for awhile before I 'got it'.
Bless!!

Answer 3

Gen 15:6 is quoted in Romans " Abram believed the LORD, and he credited it to him as righteousness." and so he is the father of our FAITH. Abraham was made righteous by faith. People of faith are therefore the SEED of Abraham, not the natural seed, the Jews.

Answer 4

We are children of Abraham if we have faith in God. Galations 3:7.

Answer 5

Through adoption into the Body of Christ we are Abraham's adoptive offspring, and by the renewal of our spirits we are his literal offspring in faith.