/How can we love and serve our brothers and sisters?/
First things first. To love others, to serve others, try to love and serve God first. Then automatically you will be in a position to love and serve all human beings, your brothers and sisters.
I am serving my disciples and trying to manifest the Supreme on earth. Right now you, my disciples, have a little faith in me; that is why you are trying to manifest the Supreme. But practically nobody is serving Him consciously. If you had really been serving the Supreme, by this time you could have offered abundant Light to the world at large. You are serving in a way, but not spontaneously, wholeheartedly and lovingly.