When Bnai Israel experienced Har Sinai- the revelation at Mount Sinai- they were completely immersed in the shechina-presence- of Hashem. After saying “na’aseh venishma”- we will do and we will hear- they became elevated to a status similar to the angels, similar to Adam before the sin, they had become immortal. Of all the generations, Hashem had chosen this generation to receive the Torah. If the people in that generation were considered to be tzaddikim-righteous- in the eyes of Hashem, how could they have committed such a transgression? And why did Hashem not protect them from sinning? Interestingly enough, Hashem allowed their pursuits in creating the golden calf because the sin would shed light for the rest of the Jewish generations proceeding them. Hashem allowed Bnai Israel to repent after the sin; hence, Hashem was showing that no matter how far we will stray as a Jewish community, there are always opportunities to do teshuva-repent. Even after the harsh sin of the golden calf, Hashem gave Bnai Israel the opportunity to repent. What a merciful G-d we have. No matter how far we stray, He always gives us opportunities to come back to Him and rebuild a relationship with Him.