If God is supposed to be immortal, how is Jesus God if He was mortal

I’ve been asked a question by a Muslim that’s kind of stumped me. They asked me something along the lines of “if Jesus is God, how could he have been God if He died on the cross while God is supposed to be immortal?” He used verses such as: > Which he will display at the proper time— he who is the blessed and only Sovereign, the King of kings and Lord of lords, **who alone has immortality**, who dwells in unapproachable light, whom no one has ever seen or can see. To him be honor and eternal dominion. Amen. - 1 Timothy 6:15-16 I’m aware that death is merely a separation of body and soul. But, if to be immortal is to never be subject to such an event, how is Jesus God if He was evidently mortal during His earthly ministry? How can you be both mortal and immortal at the same time? I’m struggling to get around the idea that this isn’t an inherent contradiction.