Does being eternally secure in Christ mean I can sin however I want?
No. Eternal security in Christ does not mean believers may sin however they want. Grace is not license, and Scripture never teaches that because we are safe and secure we are free to do as we please. Believers live in constant awareness, not wanting to fall, though they know they could.
Les teaches that eternal security is never a license to sin. He anticipates the accusation that he tells people they can do whatever they want because they will never be lost, and he answers, "Never!" Grace is not license, and Scripture does not teach that since believers are safe and secure they are free to do what they want. Instead, believers live in constant awareness that they do not want to fall or commit sin, while knowing they could. Les says he hopes never to fall into any great sin, though all are guilty of everyday mundane sins and thoughts. He points to David as an example: David was a believer who fell into great sin, yet he did not lose his salvation. David begged for forgiveness, and his conviction showed he was a true child of God; otherwise it never would have bothered him.