When reading the bible, you actions are always referred to as your right hand and you thoughts are your forehead. Jesus is the right hand of Hod kind of thing. Your forehead is where they thought their thoughts came from. So when they are saying the mark on your right hand and your forehead they are saying your thought and your actions.
Gos talks about the land of milk and honey all the time and he did call Israel his, but how does that change my statement. Isreal was a person. He talks all the time about the people of isreal (that family). Then with the new testament we are all a part of that family.
We are all sinners, we are all wrestling with God, we are all Isreal.
Paul just thought it should be a day a week not one in particular.