Godlessly is an adverb that refers to acting or behaving without any religious or moral principles. There are many synonyms for this term that can be used to convey similar meanings. Some options include unethically, immorally, wickedly, sinfully, heathenishly, impiously, sacrilegiously, irreligiously, atheistically, and god-forsakenly. Each of these words varies slightly in connotation, but all suggest a lack of regard for religious or moral values. When writing, it's important to choose the right synonym that best matches the intended meaning and tone of the sentence.