Is only believing in one God enough?

Will people that only believe that there is one God and no one is equal to him eventually go to heaven? After experiencing hell, of course. As there are many people that I know that don't follow a specific religion (but are not atheists), but believe in the oneness of God. Basically tawhid! And compare him with no other. Also there are some people who were born in Christian families, but they do not compare Jeus to God. What about them!?