Yaqin
Encyclopedia
Yaqin is the Arabic word for certainty, or that which is certain. In Islamic context, it refers mainly to total belief, without any doubt, of Allah
as the only (god) and almighty.
Allah
Allah is a word for God used in the context of Islam. In Arabic, the word means simply "God". It is used primarily by Muslims and Bahá'ís, and often, albeit not exclusively, used by Arabic-speaking Eastern Catholic Christians, Maltese Roman Catholics, Eastern Orthodox Christians, Mizrahi Jews and...
as the only (god) and almighty.