Chaim doesn't say
how people are to love Gd, just that we ought to love Gd. I'm sure that he largely was referring to loving Gd from the specifically Jewish standpoint, but there's no reason why a Christian or Noahide or even, say, a doubting Thomas can't value this wonderful message. Many people believe in Gd, but how many people truly love Gd? How many people understand that Gd offers the world commands for its own good and not simply because Gd is a tyrant or mullah? Gd wants our love just as much as he wants our understanding of why he wants us to do and not to do certain things.
For example, who is such an evil person that they don't value the commandment to honor one's parents and family?
Or who is so evil that the command not to murder is open to interpretation rather than being very clearly-defined?