One reason why I believe that personal spiritual responsibility is required

I have often said here that - in this time and place - we are required to take personal responsibility for our own salvation and spiritual development (theosis).

This applies even when we are serious members of a Christian church. 

In fact, I think all serious Christians actually do this in practice - even when they deny it in theory. 

They may state and argue that they are primarily obedient to a church; but if they are, nonetheless, real Christians - then in truth they will be practicing personal discernment with respect to that church, and (in effect) choosing what they obey - and disregarding those instructions which they regard as wrong. 

The incoherence between obedience in theory, and discernment in practice, means that such Christians are weakened and made more vulnerable in the long-term.  

Given that all major Christian (and other) Western churches are corrupt as of 2023, and getting worse; the alternative is to say and do what one believes in the heart to be wrong, and to follow an already-corrupt church ever further into evil...

Such a person cannot remain a Christian; and that will soon become publicly evident. 

He will obediently follow his church away-from Christ; which means ceasing to desire resurrected eternal life in Heaven as his primary goal. 

He will (in his heart) subordinate this transcendental Christian goal to a focus on this-world: this earthly mortal life - so that the eternal gets fitted-into the mortal. 

This because of the ever-greater convergence of his church with the evil-dominated secular-left-materialist ideology that dominates the West. To obey the church is to serve Satan, already and increasingly.