Yeshaya Hanavi writes 49 15) גם אלה תשכחנה ואנכי לא אשכחך . There is an apparent contradiction in the text. First Hashem says also these I will forget which is followed by And I will not forget? Therefore Chazal come and explain that Hashem is talking about two different major events in Jewish History. The first one which is called אלה refers to the chait of the Aigel upon which the Airev Rav proclaimed אלה אלהיך ישראל these are your deities that brought you up out of Mitzrayim. The second event was that of Matan Torah when the Luchos were given to Yisrael and begins with the words אנכי ה' אלקיך. It was then that you Yisrael said כל אשר דבר ה' נעשה ונשמע whatever Hashem will say we commit ourselves to fulfill them. That merit of Yisrael I will never forget.

The Avodas Yisrael (Balak) says in the name of the Kedushas Levi that a descendant of an illustrious religious family who continues to live his life aligned to the same tradition is not such a surprise to anyone and is pretty much expected. For choosing this lifestyle and character development he doesn't receive so much praise as the saying goes "the apple does not fall far from the tree". In contrast is the individual who comes from not such a nice family nor a religious tradition and yet he turns around and becomes a successful refined yeshiva bachur on his own, he is deserving of tremendous praise for his achievement in ruchniyus and middos.

If so why is it that Hashem holds in high esteem the accomplishment of Yisrael that they declared at Matan Torah כל אשר דבר ה' נעשה ונשמע . Their lineage stems from our holy Avos who earned the title of הם הם המרכבה they are the chariot of Hashem upon which He rode. Avraham's response to Hashem's calling his name Avraham was הנני behold I am ready waiting to fulfill your request whatever it is. The same readiness applies to Yitzchak and Yaakov. So why should Yisrael get the big applause and accolades for their נעשה ונשמע ?

The Kedushas Levi responds by saying but they did worship the Aigel after they were redeemed from Mitzrayim. What does that show? It demonstrates that Yisrael possess some impurity in their lineage (from either being an embryo in Mitzrayim their hosting mother, or an influence stemming from the Imahos who were daughters of Lavan). Yet nevertheless they still mustered up the strength on their own to declare כל אשר דבר ה' נעשה ונשמע. They therefore deserve praise for their sacrificial declaration to Hashem and His Torah.

This is what the Chazal above means. The forgetting and not forgetting of Hashem is only referring to the chait Aigel. גם אלה תשכחנה I will forget about the chait of worshipping the Aigel because Yisrael have done teshuvah. ואנכי לא אשכחך in contrast is when I remember the commitment that Klal Yisrael said at Matan Torah נעשה ונשמע there I will not forget the chait of the Aigel that they did. For by remembering the chait of the Aigel you were given boosts the merit of נעשה ונשמע to higher levels.

The passuk says וביום פקדי ופקדתי עליהם את חטאתם . Whenever Hashem remembers the mitzovs that we perform פקודי ה' ישרים, He says I will also ופקדתי remember the chait of the Aigel חטאתם. This is not to our detriment but rather for our benefit. Hashem says look how much bad you have done and yet when you choose to do miזvos it comes with a negative opposition which one has to overcome and choose the yetzer tov to abide its inclination.

במדרש שמו"ר יא ה וזה לשונו כך ישראל נתנו זהב לעגל וכו אמר הקדוש ברוך הוא יבוא זהב המשכן ויכפר על זהב העגל אמר הקדוש ברוך הוא לישראל בשעה שעשיתם את העגל הכעסתם אותי ב'אלה' אלהיך עכשיו שעשיתם המשכן ב'אלה' אני מתרצה לכם הוי אלה פקודי המשכן ע"כ והוא בא להורות שאף שהיה במשכן זהב ופר והכל מרומז על הטא העגל והיינו לפי שבשעת המצוה זכרון ההטא הוא עוד לזכותן של ישראל ועל ידי זה המצוה גדולה יותר.

For the avodah of Yom Kippur we have the application of אין קטיגור נעשה סניגור that the prosecutor cannot serve as the defender and therefore the Kohen Gadol must don clothing that is not made from gold since Yom Kippur is a day of atonement for the sin of the Golden Calf. How then can we reconcile with this, the building of the Mishkan which gives testimony that we were forgiven for that aveirah and yet many of its parts and vessels were made from gold? The answer is that Hashem wants to be constantly reminded also of the preciousness of our mitzvos in serving Him. There are no guarantees that everything will be according to His will. But our shortcomings still supercharge our mitzvos to another level because it shows that no matter what, the end core of our being is to always yearn and gravitate towards returning to our souce the Ribbono Shel Olam. אלקי נשמה שנתת בי טהורה היא.