They feared a pattern of increased taxation and restricted liberties.
After Jesus' crucifixion, his followers called him <em>Christ, </em>meaning the anointed one. The anointed one is usually transliterated into English (since it is a Jewish word) as Messiah. He is called Christ because it was believed he is the awaited Messiah in Bible.
You didn’t put choices for what we can pick from, but as far as i can see, i would put Aztec Religion!
Explaining: If they feared the Aztec people then i would assume that they also fear their religious practice!
In order to establish a system of balances to create equal division of power. They didn't want the president to have to much power because the branches might do crazy things.