Some will read this and assume unmerited blessing, some will read this and assume unmerited cursing. Solomon tells us that both come from the Lord (Ecc 7:14), so we should seek to learn in every circumstance.
In the case of Abram and Sarai the Lord has chosen out two to bless and make a covenant with despite any qualifications of which to speak. If fact when Abram is called the only things we know about him are that he is married to a barren woman and that he is the great-great-great-great-great-great-great-great grandson of Noah (Note: Noah only missed Abram’s birth by 2 years… people lived a LONG time back then). Given that God’s call on Noah was to be a “great nation” it would seem that the only qualification Abram and Sarai had was their LACK of qualification. In fact, shortly after God’ promise to Abram he tries to sell his wife into the Egyptian Pharoah’s haram to save his own skin!
In the same way, God has a call on YOUR life. Not because of WHO you are, but because of WHOSE you are. Trust Him and follow him whether you are in a time of prosperity or a time of refining. Both are a blessing and both are shaping you into who God wants you to be so you can fulfil the call He has placed on your life.
But remember! Pride comes before the fall. God pulled no punches in frustrating the plans of the people of Babel who thought more highly of themselves than they ought.
Go with God, learning in all humbleness and submission.