The parents, who can't be named for legal reasons, alleged the two boys were taken from them because of their faith, views on discipline and because they took them to church.
The case was already heard in a Family Court but a judge refused to return the children to their adoptive parents because a psychologist's report recommended against it.
Now the Court of Appeal has given permission for that decision to be reviewed.
Lady Justice Black ordered that the case should proceed to a full hearing.
She said that there should be a review as to whether the Judge at the Family Court had taken the right factors into account when deciding the boys' future, and whether he had failed to give proper weight to the good parenting that had been given to the children for three years prior to their forced removal.
The couple were being supported by Christian Concern and the Christian Legal Centre.
Andrea Williams, chief executive of the Christian Legal Centre, said: "Today's decision is an important step in seeking to secure justice for the family.
"We will continue to provide legal support for the couple as we help them to prepare for the full hearing."
The full details of the case cannot be revealed in order to protect the identity of the two boys.