Saying no to sin is possible. In fact the remnant of GOD do not live a sinful lifestyle. Christians are often attacked with the argument that no one is perfect everybody sins. But this argument is misguided because we are talking about living a lifestyle without the propensity to sin and not perfection.
Excusing sin because we can not reach perfection is like telling a man why walk anymore since one day you slipped and fell. For the Christian sinning is the exception and not the rule but for sinners, sin rules.
1 John 3:6 No one who abides in Him [who lives and remains in communion with and in obedience to Him--deliberately, knowingly, and habitually] commits (practices) sin. No one who [habitually] sins has either seen or known Him [recognized, perceived, or understood Him, or has had an experiential acquaintance with Him]
