Ok, thanks. Just so I’m clear, Church teaching on what is and what is not a mortal sin and the teaching that mortal sins may not be forgiven without confession (unless perfect contrition is there) and venial sins may be forgiven without Confession are rules that were in place at the very beginning of the Church and have never changed or evolved. Is this a correct statement?
Ditch the word ‘rules’ altogether and you’d be closer.
After all, the Church didn’t make ‘rules’ that God is Trinity, that Jesus is both fully man and fully divine, or that certain books are inspired scripture. What it did was teach Divine knowledge and Divine truths about these things that were revealed to it by the Holy Spirit.
Now - have all these divine truths been taught since the beginning of the Church and never changed? They HAVE always been truth, no mistake about that - God HAS always been Trinity, Jesus WAS fully human and fully divine, and certain writings ARE inspired scripture. Whether they were always explicitly taught - well, we don’t have complete records from all who taught, so we don’t really know. Some of them certainly were.
The important thing is that they always WERE true, even during the first two or three centuries when there was debate about the Trinity, about whether Jesus really was both divine and human, or about which books should be included in scripture (which there still is today, of course).
These things didn’t BECOME true only when they were pronounced as dogma at the Councils of Chalcedon, Nicea, Hippo and Carthage.
So in relation to sin - the truth that the Church teaches today about sin has always been true, and certainly is implicit in one of John’s epistles, which distinguishes clearly been sins that are ‘unto death’ (mortal) and sin which is NOT ‘unto death’ (venial). Even if all of it hasn’t always been explicitly taught or formalised as dogma, it is true and to be believed. The nature of sin doesn’t change, although our understanding of it, and God’s revelation of it to us, can. Just as His revelation of Himself changed from OT monotheism (since Christ had not yet been incarnated) to Trinity in the NT.