You can take Acts 15 to justify anything. ("Well, the old law no longer applies and the Apostles never said you can't kill somebody, so it's all good, as long as you believe that you're "saved".). /s)
Please reread the entire chapter I posted. The context is legalists telling new Gentile believers they had to follow the Law of Moses.
A council was called.
The Holy Spirit led the Apostles to write a specific letter telling them they would do well if they just did these things...
Greetings. 24 We have heard that some went out from us without our authorization and disturbed you, troubling your minds by what they said. 25 So we all agreed to choose some men and send them to you with our dear friends Barnabas and Paul— 26 men who have risked their lives for the name of our Lord Jesus Christ. 27 Therefore we are sending Judas and Silas to confirm by word of mouth what we are writing. 28 It seemed good to the Holy Spirit and to us not to burden you with anything beyond the following requirements: 29 You are to abstain from food sacrificed to idols, from blood, from the meat of strangled animals and from sexual immorality. You will do well to avoid these things.
IF the Holy Spirit was going to keep Gentiles under Law, this was the time to clearly state it. They did not. They wiped it away and listed 4 things.
There's all the authority any Christian needs. A passage in Scripture, the Holy Spirit, and the Apostles.
If you wish to ignore or deny it, no problem.
But in the end, Rome is not needed to tell Christians what day to worship.
While Rome will allow an APPARITION to teach anything!