What is Kufr/disbelief? What is faith/Eman?

This is a definition that my teacher taught me.

Kufr or disbelief is that someone disbelieves in what the Messenger of God Muhammad (peace and blessings of Allah be upon him). This is not the Muslim god because God is for everyone but its based on the belief on the final Prophet that the people will be judged.

The definition of belief or Eman is the affirmation on the tongue to what the heart beliefs with the condition of not carrying out an act of disbelief like throwing the Quran away.