Jehovah's Witnesses are a works-based faith group, whereby they believe they need to perform certain works in a certain way and with a certain level of faithfulness in order to receive justification and, ultimately, salvation*. They believe that they can earn God's favour and grace and that somehow it's up to them to "keep themselves in God's love"**.
The Bible, teaches, however, that it's faith in Jesus that rewards us with salvation, as it's Jesus's righteous work at Calvary that is the only work that saves. This is a gift from God and cannot be earned.
So, my question for Jehovah's Witnesses is, how much of your salvation is dependent on you, and how much on Jesus's righteousness? 5% you 95% Jesus? 23% you 77% Jesus?
*by salvation I mean that they won't be destroyed at Armageddon.
** the Governing Body of Jehovah's Witnesses have condensed their guide to living correctly as a Christian into a book called "Keep Yourself in God's Love". This book contains rules that Jehovah's Witnesses follow regarding extra-Biblical matters such as masturbation and blood fractions.