How does such a doctrine find sway if it is not biblically viable?
2 Timothy 4:
3 For the time will come when they will not endure sound doctrine, but according to their own desires,
because they have
itching ears, they will heap up for themselves teachers; 4 and they will turn
their ears away from the truth, and be turned aside to fables.
It is easy grace. The fable that grace covers all your past, present and future sins, and still go to heaven. In other words, telling people that you can have your cake and eat it too. That is behind this whole false doctrine that Jude 1:4 called turning the grace of God into licentiousness. Licentiousness is a license to sin with no consequences.
Besides "cover" there are other key phrases of the false doctrine of the Church age of Sardis in Revelation 3.
False Doctrine phrases
Cover: the blood of Jesus covers our sin, and hides our sin from the Father who cannot look upon sin.
Past,
present and future sins are all forgiven
Imputed righteousness, that covers your unrighteousness.
Jesus freed us from the law and the
consequences of sin.
Truth
The blood of Jesus
takes away our desire to sin 1 John 3:5
Past sins are cleansed. 2 Peter 1:9
Our born again nature does righteousness. 1 John 3:7
Jesus freed us from SIN. John 8:34-36