Three of your concerns are addressed here - Lydia, and Calvinism, and last what I saw in your OP.
In the post of yours I answered was a reference to Lydia that I did not acknowledge to you, but will here for it is a good opportunity to show I believe Lydia was a worshipper of Yahweh, just as you say. So we say the same thing, but say them differently. Yet there are deeper things here we probably do not agree on. However our believing Lydia was a worshipper of Yahweh doesn't mean we understand the Body of Christ alike.
I say there is a reason for Saul/Paul, and Damascus Road, and the intervention of Jesus Christ from heaven. Why was Lydia water baptized, and included her family? She was of those promised the Kingdom, so the Great Commission applied to her. We know the Acts period was a time of translation, a time of displacement of the original (Old) to something better (completely new). Missing this understanding puts us on the road to continue in believing the Great Commission. Lydia is a Kingdom Saint; I am not, for I am in the Body of Christ. We are connected with those of the Kingdom belief, which are those that hold onto Water Baptism, arguing either it most certainly should be done, either before or after salvation.
If we remove Water Baptism as a requirement, then we can see very clearly the light that was revealed to Paul over time for we Gentiles today. It is different from that given specifically, and to them (and their whole family and household) only. But NOW it is remission of sins Through Faith only, with One request. We are to remember Him in One way, and I don't believe it is at Christmas time, as man has told us o do.
We are on the same foundation of the Covenant people, but are we They? The One circumcision and baptism done without hands makes us One. We are told there is One Body, One Sprit, called in One Hope; One Lord, One Faith, One Baptism, One God and Father of all (Ephesians 4:4-a5).
Then to disciples of Calvinist, and Arminian, as well as others are disciples of Jesus Christ. "Now this I say, that every one of you saith, I am of Paul; and I of Apollos; and I of Cephas; and I of Christ. 13. Is Christ divided? was Paul crucified for you? or were ye baptized in the name of Paul? 14. I thank God that I baptized none of you, but Crispus and Gaius," I Corinthians 1:12-14. If we will follow Paul to II Corinthians, we find something different, and thereafter as the revelation of Paul's Gospel from Jesus Christ is presented to us. Any further reverence we may find from Paul as to Baptism, has nothing to do with Water Baptism. By this time we can notice that really All Now are considered to be Gentile, leaving behind the Great Commission. Of course Hebrews is written to whom it says, which tells us is talking directly to them.
To end, I saw in your OP we say the same thing, but differently, and I notice a switch took place. Things like Paul Was set apart; Through His Grace, Reveal His Son in me, and preach His Gospel among the Gentiles. So we say the same things. but differently. I say the same things as you, but you see error in what I say, and contend a bright light was not turned on.