In the Book of Matthew, where the Judgment Day is depicted for us in the imagery of One seated upon a throne and dividing the sheep from the goats, the test of a man then is not, "How have I believed?" but "How have I loved?" The test of religion, the final test of religion, is not religiousness, but Love. I say the final test of religion at that great Day is not religiousness, but Love; not what I have done, not what I have believed, not what I have achieved, but how I have discharged the common charities of life. Sins of commission in that awful indictment are not even referred to. By what we have not done, by sins of omission, we are judged. It could not be otherwise. For the withholding of love is the negation of the spirit of Christ, the proof that we never knew Him, that for us He lived in vain. It means that He suggested nothing in all our thoughts, that He inspired nothing in all our lives, that we were not once near enough to Him, to be seized with the spell of His compassion for the world. It means that—
"I lived for myself, I thought for myself, For myself, and none beside— Just as if Jesus had never lived, As if He had never died."
You can find the book online here. For Christians, I think this is a good reminder that loving one another is what really matters; as opposed, say, to disputes about fine points of doctrine. And whether Christian or not, I think you can be inspired by the idea that the most important thing in life is love. Thanks to Robin Parry for quoting from this passage in his post What is "a good Christian"? over at Theological Scribbles.