Scripture reveals Lucifer was the most beautiful Angel in Heaven, but Lucifer was unthankful and rebelled against God. Adam & Eve was given every tree in the garden to eat from except one, and they were unthankful. God delivered the people of Israel from Egypt with miracle after miracle showing his love and mercy time after time but they were unthankuful and because of unbelief entered not into the promised land.
"In every thing give thanks: for this is the will of God in Christ Jesus concerning you." 1Thessalonians 5:18 "This know also, that in the last days perilous times shall come. For men shall be lovers of their own selves, covetous, boasters, proud, blasphemers, disobedient to parents, unthankful, unholy," 2Tim 3:1-2