Abraham is tested by God to sacrifice his son Issac. This comes right after Abraham gives Sarah to Abimelech because he is afraid he may be killed. How could he so readily give up his wife when it comes to his life and so readily give up his son to obey the very God he did not trust in the previous chapter. Ge 21-22
I believe this is a great example of how an anointed person in covenant with God can be fallible. Why would Abraham enter a relationship with Hagar when God had promised a son with Sarah? Why was Abraham afraid of Abimelech and created a lie and seemed willing to suffer the loss of his wife? (And why would Abimelech fall in love with this older woman?? This is unrelated…)
The Bible does not follow the typical mythical literature of making the heros sound great when they aren’t or excusing their behavior. It seems that Abraham had his own struggles in faith. Even though he was willing to follow God and regarded as greatly faithful (Heb. 11:8-12), he still struggled along the way. However, God showed His faithfulness (1 Tim. 2:13) even when His people are not.