They are not in the house prior to faith. They stand outside the house. They have the key of faith; which they use to open the door of the house (Jesus Himself). They put the key in the keyhole, open the door, and walk into the house. Once they are in the house, they are standing in grace.
Consider the context in Hebrews 8:8-10. It says that the Lord writes the law in the heart and on the mind of the New Covenant believer in Christ.
So then, under the New Covenant, we obey the law (see also Romans 13:8-10, Galatians 5:14, 1 John 5:3, 2 John 1:6, Romans 8:7, Romans 8:4, Galatians 5:22-23).
Preaching the law does not place anyone under a curse. The law is a schoolmaster to lead men to Christ (Galatians 3:24) so that they might understand that they are sinners in need of a Saviour (Romans 3:20) in order that their souls might be converted (Psalms 19:7 (kjv)).
The devil often quotes half a verse in order to get his point across.
Here is the whole verse:
Gal 3:10, For as many as are of the works of the law are under the curse: for it is written, Cursed is every one that continueth not in all things which are written in the book of the law to do them.
It actually says, in the kjv,
"
For by grace are ye saved (?)
through faith..."
The nkjv is watered-down just a little...not as bad as some others; but still watered-down.
Amen. Whosoever is forgiven much, also loves much (Luke 7:36-50, 1 John 4:19, Romans 5:5).