So, if someone believes in a heavenly Father who hasn't sent His own Son to die for everyone to remove their sins and allow me a way into into his kingdom by grace, that God is a lie?
Strawman argument...sorry, not going for it...
The question posed by you "is the god (allah) in Islam the same as the Jewish and Christian God...
The answer is no based on the way the religion is practiced...they are diametrically opposite...one must be a lie...
To answer your strawman question in a roundabout way, almost every major religion outside of the Christian, Jewish faith, do not have a single deity to worship...makes you question a moot one..