In one sense, the ONLY way you can serve God is to serve your neighbour. God doesn’t need anything from us, so the test He has set us is how we will serve Christ in the form of the “least of these my brothers”. By becoming human, and “drawing all men to Himself”, He has made the "least of these my brothers’ His proxy on earth.
I’ve said ad infinitum that the night my father died, he appeared in my room. At one stage I got very angry about the way he’d deliberately wrecked my vocational aptitudes, which he had. But he commented, “it’s not even important!”, which was an insight he could see from where he was. In other words our careers and status in society are, in God’s eyes, unimportant. We think they’re important, but He doesn’t. “What men think wise is foolishness in God’s eyes” as Paul wrote.
When I responded, “Then what is important”, my father’s apparition replied, “How you treat other people”. It appears that will be one of the main litmus tests that all of us will be subject to. How we served our neighbour will be a critical area when we face our own judgement, for that is how God will judge whether we’ve served Him or not.