Born again Christians whom are "in Christ" are condemned by the Roman Catholic Church (RCC). Over 100 anathemas have been pronounced against Christians by the Roman Catholic Councils of Trent and Vatican II. The RCC considers their "condemnations" against Christians who are not members of the RCC still in effect today (even if some RCC members themselves do not) and the RCC asserts that their "condemnations" can only be lifted if a Christian returns in submission to the authority of the pope and the RCC.
The truth, of course, is that there is only one door to enter the
church (1) and that door is Jesus Christ. He alone, by His Spirit, admits people into His church no matter their membership, or lack of, in any Protestant or Catholic religious organization/church.
And afterwards, "Therefore there is now no condemnation for those who are in Christ Jesus. For the law of the Spirit of life in Christ Jesus has set you free from the law of sin and of death. For what the Law could not do, weak as it was through the flesh, God did: sending His own Son in the likeness of sinful flesh and as an offering for sin, He condemned sin in the flesh, so that the requirement of the Law might be fulfilled in us, who do not walk according to the flesh but according to the Spirit." -Romans 8:1-5.
(Note Romans 8:9 which states that if anyone does not have the Spirit of Christ, he [that person] does not belong to Him [Jesus Christ] no matter their membership, or lack of, in any Protestant or Catholic religious organization/church).
"So then brethren we are under obligation, not to the flesh, to live according to the flesh for if you are living according to the flesh you must die; but if by the Spirit you are putting to death the deeds of the body, you will live. For all who are being led by the Spirit of God, these are sons of God. For you have not received a spirit of slavery leading to fear again, but you have received a spirit of adoption as sons by which we cry out, “Abba! Father!” The Spirit Himself testifies with our spirit that we are children of God, and if children, heirs also, heirs of God and fellow heirs with Christ, if indeed we suffer with Him so that we may also be glorified with Him." -Romans 8:12-17.
When by faith one receives the initial act of salvation (justification), at that very instant he or she is sealed by the Holy Spirit, baptized into the body of Christ, redeemed, regenerated, born again, adopted into God's family, reconciled to God, and forgiven of sin based on the mediation and atonement of Christ. All of these saving acts are made possible only because of the substitutionary death of Jesus on behalf of our sins, whereby the Just died for the unjust in order that God's justice may be satisfied and His mercy justify the unjust.
But salvation does not end with a single act of justification; this is only the first stage, by which one is saved from the penalty of sin. Salvation also involves a lifelong process of sanctification, by which we are saved from the power of sin. At death, our redemption climaxes with an act of glorification that saves us from the very presence of sin. At this point we will see God face-to-face (in the Beatific Vision) and become like Him, for then we shall see Him as He is.
The RCC is amiss in their condemnations of
us whom are "in Christ" and part of His church.
And yes, the RCC
misinterpreted Matthew 16:18.
(1) Believers joined to Christ's spiritual body by the Holy Spirit (1 Cor. 12:13) at the moment of regeneration (Titus 3:3-6) when they individually place their faith in the Lord Jesus as their Savior (Acts 16:31).