What if earth was spinning at the speed of light

The Earth makes one full rotation on its axis every 23 hours, 56 minutes and 4.1 seconds. And it’s not moving at the same speed everywhere. The rotational speed varies depending on your distance to the poles. This rotation makes Earth suitable for life. The diurnal cycle, or the shifting between day and night, helps keep the planet at a habitable temperature. Earth’s rotation is the driving force of weather patterns. Even tides are affected by the Earth’s spin.
So if we were to accelerate this rotation, would we completely destabilize the climate? What would happen to the length of our day? What geographical and climate changes would occur? And at what point would life on Earth cease to exist?