In Parashat Lech Lecha, Avraham Avinu goes through trials and tribulations. Hashem tells Avraham to leave his homeland and go to Canaan which they then have to leave because of a famine. In Egypt, Avraham has to fend off one king from stealing Sarah from him and then four more to keep them from “looting” Lot. And we groan when our parents ask us to help around the house. At the end of all this traveling and struggling to survive, Avraham is rewarded for his great faith in Hashem with just a letter added to his name?
This seemingly small name change has huge consequences. Berachot 13b records a Machloket about whether calling Avraham (for non-Torah purposes) by the name Avram is a violation of a Mitzvah Asei or a Mitzvah Lo Ta’Asei . Why would the pitfalls of this commandment be so large?
Additionally, Avraham adds a letter to his name, as opposed to Sarah who only switched a letter. This seemingly reminds us of Avraham Avinu’s past in Aram (Avram means father of Aram) while also signifying a new chapter of Avraham’s life, the father of monotheism. What is with all of this confusion?
To answer, I cite a concept from Rav Fridman Shlita’s Gemara shiur. In the Kiddushin process, if a Rasha gets married on the condition that he is a Tzaddik, the Shulchan Aruch writes that the marriage might be valid because the Rasha might do Teshuva in order to be considered a Tzaddik. What’s the reason for this uncertainty? The Rasha says he will do Teshuva but we don’t know if he actually will. A parallel can be drawn to Avraham Avinu. Chizkuni says that Avraham travels to Egypt and he is a little doubtful about Hashem’s ability to protect him, which is why he tells Sarah Imeinu to say she is his sister. Similarly, Avraham is offered loot after defeating the four kings and suddenly Malkitzedek jumps in. He reminds Avraham that Hashem is the ruler of the earth, and then suddenly, Avraham refuses any of the spoils for himself.
These two examples do not imply that Avraham was not great; he was just getting into situations that require more trust in Hashem than all of us will ever have. Maybe he did fully trust Hashem in Egypt or would always have turned down the loot from the kings, but the critical point is the uncertainty. That is what the Hay in Avraham’s name comes to do: to help him make a concrete decision that going forward he will always trust in Hashem. Going back to the Rasha who says he is a Tzaddik, we consider him a Tzaddik if we see him giving up his evil lifestyle and doing good deeds instead of just saying he will. When Avraham receives Hashem’s name - the Hay - in his name, we see that not only does Avraham want to dedicate his life to Hashem, but he commits to doing so.
To answer the other questions is now simple. Hashem doesn’t drop any letters from Avraham’s original name because it reminds all of us that Avraham came from a family that worshipped idols and then morphed into perhaps the father of monotheism. That is why we can refer to Avraham as Avram when learning Torah but not otherwise: if we are saying it in a derogatory manner because we grew up in Torah households while his family was idol worshippers, it degrades the Torah and is anathema. However, if we are saying it out of respect for all the growth he achieved and the challenges he overcame, it is unquestionably permissible. Thus, we can learn from Avram turning into Avraham that we too can become great people with the help of Hashem.