You're missing my point. I'm saying that apostolic succession is
NOT THE TEST for the true religion.
Of course the apostles didn't have the Bible, and yes the apostles did train the next generation of disciples (but they did impart the Gospel to them).
Even Paul, had mentioned problems about false teachings and some early Christians (some of whom no doubt were taught about the Gospels) were peddling heresies!
Galatians 1
No Other Gospel
6 I am astonished that you are so quickly deserting the one who called you to live in the grace of Christ and are turning to a different gospel— 7 which is really no gospel at all. Evidently some people are throwing you into confusion and are trying to pervert the gospel of Christ. 8 But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let them be under God’s curse! 9 As we have already said, so now I say again: If anybody is preaching to you a gospel other than what you accepted, let them be under God’s curse!
What is false doctrine? | GotQuestions.org
When the Bibles became available, through all the centuries even to the present - all Christians can trace their belief to the Gospel (given by the apostles).
A lot of churches that teaches false teachings can trace the origin of their belief back to the Gospels, however they'd corrupted the Gospel.
The true church does not deviate from or corrupt what is written in the Scriptures. Consistency and alignment with the teachings in the Scriptures, determines the true church!