1) Mocking God - We can deceive ourselves and not even realize it until it is too late. Remember God has given you His Spirit, if you are His, but there is an evil opponent that you have who seeks to steal, kill and destroy you and he does it sometimes by trying to deceive you through events and actions in your life. Here Paul is telling us that we sometimes choose to deceive ourselves in our actions and thoughts. It may not be the direct action from our enemy, satan, although he many times is the underlined reason of our deception, but we alone can deceive ourselves. In doing whatever is deceptive, those persons have sought to mock God. But our God who is all wise and sovereign, He cannot be mocked no matter how smart we might be.
(To mock - is “to snub or turn up your nose.” Or, “to sneer with the nostrils drawn up in contempt.” Or, “to turn up the nose in scorn; hence to mock, or deride, or insult. The sense is, that God could not be imposed on, or could not be insulted with impunity, or successfully. To mock is, properly, (1.) to imitate, to mimic; to imitate in contempt or derision. (2.) To deride, to laugh at, to ridicule. (3.) To defeat, or to illude, or to disappoint. (4.) To fool, to tantalize-(Webster.) Here it cannot mean to imitate, or to mimic, but it refers to the principles of the Divine administration, and must mean that they could not be treated with contempt, or successfully evaded. They could not hope to allude or impose on God.” Barnes' Notes on the New Testament.)