Is it allowed to invite guests whom are not religious, when they can come over to walk but they will take their car? And when you don’t invite them the will also not keep the Shabbat! Is there an existing psak?

You are allowed to invite non-religious guests to visit on shabbat if they can walk over. You should not inquire how they plan to come. If they tell you they are driving, you are not allowed to say "come by anyway"- just tell them that it is possible for them to walk and you hope they do (see Shu"t Tzitz Eliezer 6,3).