So if a believer in Christ facing God, confesses his sins to God the Father, ...will God forgive those sins, if another believer doesn’t forgive them? What if a RCC priest doesn’t forgive them? Do you claim God rejects any prayer by a believer seeking to confess His sins through faith in Christ?
Seems like a very poor stance in the RCC denomination.
Those questions are answered in the Catechism. I encourage you to read it before you make your assumptions and merely denounce it as a “very poor stance”.