The answer is .... drum roll please....
Zero.
As far as forgiveness of sins - only ONE has that right and power - Jesus Christ. No-one on this earth has the power to "save" or to "dole out" forgiveness.
Jesus Christ told many people "your sins are forgiven you". That is HIS right and position to do.
Any "my own personal interpretation" arguement won't fly... My keys to interpretation of scripture are quite simple:
Pre-reading- Prayerfully approach the LORD to open my eyes, heart, and mind to what HE has to say to me through HIS word.
Then:
Step 1 - Read God's word - IN CONTEXT. What does it SAY? (Remember the old saying - text, without context, is nothing but a pretext).
Step 2 - If Step one does not reveal what is said, then how does it read in relation to other parts of the scripture that address the same issue or deal with the same topic?
Step 3, if 1 and 2 do not clarify, then go to the original language (Greek and Hebrew for the most part). What were the words we reading translated from? What did those words mean to those at the time of the writing?
It is also a good idea to not approach scripture with pre-conceived notions - that taints our interpretation.
I find that very little requires a great deal more than the above 3 steps. I freely admit that I have used commentaries from various sources, as well as multiple translations for comparison purposes.
The Great Commission, as many of us call it (Matthew 28:18-20) is probably the most clear picture of our duty as believers in Jesus Christ. WE are to share the Good News (The Gospel) with the world. Seeking out the Lost (those who have not placed their faith and trust in Jesus Christ ALONE for their salvation - eternal life), and by sharing the message of God's perfect love for us, hopefully helping them transfer their trust to Christ - thus being "saved" from eternity in Hell. But we do not have the power to prevent someone from being saved through faith. We are granted the privilege of helping to spread HIS message.
The Holy Spirit enters the believer at the moment they place their faith and trust in HIM. Some argue for an additional "baptism in the Spirit", which appears, from a New Testament point of view, to be the additional blessings and empowerment, much like the disciples experienced on the day of Pentecost. Again, this is not bestowed by any person.
Christ did not have to "condone" marriage via His miracle at the wedding - Marriage between one man and one woman are spoken of throughout the Bible as being what is ordained by God. 1 Timothy is pretty clear about the importance of Pastors and Deacons being "husband of one wife".
Why must I continually be getting "forgiven of my sins"? How many times did Jesus die on the cross? Once. Christ died once and for all - for ALL sins. Those sins are forgiven - past, present, and future sins - when we accept Christ as our savior. Back to the example of Christ's healing of so many sick - with the accompaniment of "your sins are forgiven you"... Their healing came about because of faith. When your faith is in Christ - your sins are forgiven. The physical healing was an external picture of what happened in their heart and soul.
Reconciliation between sinful man and the Perfect God comes only ONE way - that is through the atoning blood of Christ who was our propitiation (I love that word!). Christ paid our sin debt - 100%. But we are still not reconciled until we have placed our faith and trust in Jesus. A faith and trust that goes beyond a head knowledge. WE cannot reconcile ourselves to God through our good works. "For it is by Grace ye are saved, not of yourselves, it is a gift of God, not of Works, that none may boast." (Ephesians 2:8) Works are the natural outpouring of a heart turned completely to God. As Paul states - Show me your faith without works and I will show you my faith BY my works. They are the result of a heart like Christ's - one that sees the world out of compassion and love. Not out of a feeling of duty or to gain. Works done with gain in mind are burned up as chaff...
Baptism, the beautiful picture of our death, burial and resurrection in Jesus Christ. It is also an outward sign of the "new man" we are to put on when we follow Christ in Faith. Baptism never saved someone's soul. But it is a sign of obedience to HIS will. This ordinance is carried out, as Biblically directed, when a person has come to saving faith in Jesus Christ. Believer's Baptism. You used John the Baptist as example - What did John tell those Pharisees who asked to be baptized? He turned them down, because they had not repented of their sins. And the method is even clearly presented - immersion. How else could Christ have "come up straight away"? The same question with the Ethiopian Eunuch - who was baptized by Philip. The Eunuch heard the Gospel and desired to be baptized because of his faith.
Lord's Supper (aka - Holy Communion) - An ordinance of the church that has so much meaning - but does not, in and of itself, provide salvation or forgiveness of sins. Quite the contrary - the admonition to not "partake of the cup unworthily" - because NONE of us are "worthy", but we are to examine ourselves - The cup is not for those who do not have their faith in Jesus Christ, nor is it for those living lives of intentional sin. The Lord's Supper is an act of remembrance of what Christ did for us - through his body and blood - the perfect sacrifice for the whole world. It is both a celebration, and a remembrance of what was required for payment of our sin. (Do this in remembrance of Me).
These last two, Baptism and the Lord's Supper - ordinances prescribed by God, through Jesus Christ, both with symbolic and spiritual value. But neither imparts "salvation" or "forgiveness". That is only granted by God, through, by, and because of Christ Jesus.
And by the way, I grew up Episcopalian (I am no longer a member of that denomination - far from it). But that background gives me a bit of insight into Catholic teachings because of the many similarities (and in church history, the Anglican Church was FAR more like Catholic - just minus the Papal authority).
And I will leave you with Hebrews 4:14-17 -
Seeing then that we have a great high priest, that is passed into the heavens, Jesus the Son of God, let us hold fast our profession. For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin. Let us therefore come boldly unto the throne of grace, that we may obtain mercy, and find grace to help in time of need.
Where does the Bible state that it is the sole or final authority of Christianity? .... drum roll please ...
Answer: nowhere.
Is the Bible the sole "teaching from God?" No. The Bible Itself states that there are "oral" teachings and traditions that are to be carried on to the present-day (2 Thessalonians 2:15; 1 Corinthians 11:2; 2 Timothy 2:2; Romans 10:17; 1 Peter 1:24-25). These teachings are what the Catholic Church considers "Sacred Apostolic Tradition." This type of "Tradition" never changes because it was passed down by the Apostles themselves. It is not the same as the man-made traditions condemned in Scripture.
Jesus Christ told many people "your sins are forgiven you". That is HIS right and position to do.
He still does but now it is through His priests - John 20:22-23 - directly out of Scripture - no interpretation needed.
Any "my own personal interpretation" arguement won't fly...
Of course not because personal interpretation is not condoned in the Bible (2 Peter 1:20). Was individual interpretation of Scripture practiced by the early Christians or the Jews? Again, "NO" (Acts 8:29-35). The assertion that individuals can correctly interpret Scripture is false. Even the "founder" of Sola Scriptura (Martin Luther), near the end of his life, was afraid that "any milkmaid who could read" would found a new Christian denomination based on his or her "interpretation" of the Bible. Luther opened a "Pandora's Box" when he insisted that the Bible could be interpreted by individuals and that It is the sole authority of Christianity. Why do we have over 35,000+ different non-Catholic Christian denominations? The reason is individuals' "different" interpretations of the Bible.