I could have gone on and on with the evidence. But, in the end, true belief requires a step of faith - there comes a point when we all have to decide that it's all either true (there is a God, He created the heavens and the earth, He sent His only begotten son to die on the cross for the sins of all of us - even those who called out for Him to be cricified, and He rose from the dead to be seated at the right hand of the Father), or it's not, and then live accordingly.
I made that decision many years ago and have seen nothing since that causes me to question that decision. In fact, the more I learn, the more I am convinced that my decision was the correct one.
He sent His only begotten son to die on the cross for the sins of all of us
...if I were to quibble with any part of Christian ecclesiology,(note that I use the subjunctive) it would be with the concept of sacrifice serving as the remediator of sin...inasmuch as sin is inevitable in the human species, and such remediation would have to be occurring on a non stop basis in order to effect the desired change...
...so were humans more sinful before Christ than after, or not...and if not, why not...because if not, then mankind’s essence hasn’t changed through his contact with Christ (and I think we’d be hard pressed to argue that mankind is less sinful today than in antiquity)...
...but, in the end, like everything else, it could all turn on semantics...just what is entailed in the term ‘sin’...