Of Course the shaiytan believes in Allah...This is why it is important to not only Believer in Allah but to Practice what Allah tells us....otherwise if we only believe without practice we are similar to shaytan
Esselamu alejkum
ALL-LLAH swt will never forgive shaytan
At the day of judgement ALL-LLAH will be
so merciful and when shaytan will see that
he'll think ALL-LLAH will forgive him.
We believe in ALL-LLAH but we must
accomplish our obligations(fards) ,we must
work according to ALL-LLAH's law which is
Kur'an and we should follow sunnah of
rasulullahi saws.Be a good muslim.Leave
dunya cause it is a short century.The only
mission of people in this dunya is to adore
ALL-LLAH swt.Wesselamu alejkum we rahmetullah