Genesis 12:1-3
Now the LORD said to Abram, "Go from your country and your kindred and your father's house to the land that I will show you. 2 And I will make of you a great nation, and I will bless you and make your name great, so that you will be a blessing. 3 I will bless those who bless you, and him who dishonors you I will curse, and in you all the families of the earth shall be blessed."

What does 'blessing' mean? It contrasts so obviously with 'luck', which is the usual channel by which expect to receive good things. Blessing indicates that God is the source of good things. But it is also an act of speaking, not merely showering good things upon the person. A blessing is a promissory note, or, perhaps, an invocation of the goodness of God. It is something said, as well as something done.

Blessing all the families of the earth is the point of God's election of Abram. His purpose in selecting is to include; though this is not without its exclusionary impact either. In this key passage, Abram is singled out not only for blessing but that he might 'be a blessing', through the making great of his name. The greatness of his name seems to be part of the blessing, but also the means by which the blessing goes out to ... well, whom? God will 'bless those who bless him'. Reactions to Abraham as the holder of the divine promise and the bearer of the divine favour are a signal of how it may go for a person vis a vis the Lord.

But here, already, is an apparent tension between the universal scope of the blessing to be introduced through Abram, and the fact that not all will accept it. Through Abram, all of the families of the earth will be blessed. But, there will indeed be some who curse him, who God will curse in turn. This is, of course, a part of the blessing to Abram - his protection and vindication against his enemies. The blessing is not without its cursing: it is universal, but not all-inclusive.