Reading Deuteronomy 27:26 reminds me of the reformed theological position that as Christians our obedience confirms our state of salvation (rather than earning our salvation).
“‘Cursed be anyone who does not confirm the words of this law by doing them.’ And all the people shall say, ‘Amen.’
(Deuteronomy 27:26 ESV)
The context here in Deuteronomy is of ‘sealing’ or confirming agreement with the terms of the covenant by actually obeying it. So also the seal, or outward sign, of my participation in the New Covenant is my obedience to Christ.
Unfortunately for the people of Israel, the perfect obedience required by the law is impossible for anyone to achieve. Therefore disobedience to the law brings a curse upon those who attempt to live by the law. The only way to be free is to have that curse removed somehow, which of course is exactly what Jesus Christ did by taking the curse upon Himself (Galatians 3:10-14). As a Christian I am enabled to obey Christ by the Holy Spirit who is the seal of my salvation and gives the ability to walk in obedience to Christ (see Ephesians 1:13-14).