diff --git a/ImperatorToCK3.sln.DotSettings b/ImperatorToCK3.sln.DotSettings
index f119f92a2..26e8390f3 100644
--- a/ImperatorToCK3.sln.DotSettings
+++ b/ImperatorToCK3.sln.DotSettings
@@ -79,6 +79,7 @@
True
True
True
+ True
True
True
True
diff --git a/ImperatorToCK3/Outputter/OnActionOutputter.cs b/ImperatorToCK3/Outputter/OnActionOutputter.cs
index c0faf9a61..f5bd8c67d 100644
--- a/ImperatorToCK3/Outputter/OnActionOutputter.cs
+++ b/ImperatorToCK3/Outputter/OnActionOutputter.cs
@@ -33,6 +33,37 @@ public static void OutputCustomGameStartOnAction(Configuration config) {
if (config.LegionConversion == LegionConversion.MenAtArms) {
writer.WriteLine("\t\tset_global_variable = IRToCK3_create_maa_flag");
}
+
+ if (config.FallenEagleEnabled) {
+ // As of the "Last of the Romans" update, TFE only disables Nicene for start dates >= 476.9.4.
+ // But for the converter it's important that Nicene is disabled for all start dates >= 451.8.25.
+ writer.WriteLine("""
+ # IRToCK3: disable Nicene after the Council of Chalcedon.
+ if = {
+ limit = {
+ game_start_date >= 451.8.25
+ }
+ faith:armenian_apostolic = {
+ remove_doctrine = unavailable_doctrine
+ }
+ faith:nestorian = {
+ remove_doctrine = unavailable_doctrine
+ }
+ faith:coptic = {
+ remove_doctrine = unavailable_doctrine
+ }
+ faith:syriac = {
+ remove_doctrine = unavailable_doctrine
+ }
+ faith:chalcedonian = {
+ remove_doctrine = unavailable_doctrine
+ }
+ faith:nicene = {
+ add_doctrine = unavailable_doctrine
+ }
+ }
+ """);
+ }
writer.WriteLine("\t}");
writer.WriteLine("}");