Just as it has ever been, in its 3000 or so year history, believers and scholars constantly interpret, parse, translate, and re-interpret this extremely complicated book of books. Those practices which were seen as problematic in any given era, were found to be proscribed by the Word of God. Those which were proscribed in earlier periods but the culture had moved along and either no one cared any more about that or the opportunity to practice it no longer existed, just fell out of discussions. It’s a very big long old book, and figuring out what God had in mind when they inspired someone to write something down, at a time when virtually every single thing was different than it is now, is, um, challenging. Translations continue to be refined and argued.
Conservative Christians look mainly to the violent and punitive and often mysteriously arbitrary Hebrew god, and also some particular letters of Paul, to justify their punitive and narrow beliefs. Liberal Christians rely heavily on the Gospels, and what Jesus was remembered to have said. Paul was concerned to build a cohesive church of former gentiles, jews, and any others, who all adhered to the precepts and salvation history which he frankly was the main author of. He lived in a particular time, in the swirl of Roman, Greek, Jewish, Zoroastrian, and other religions that the Roman Empire had drawn into its vast sway. His ideas were formed by his time and by his own vision. As a Pharisee, he was appalled by what he saw as the licentiousness of some Greek sexual practices as well as the bacchanals of Rome, and his writings reflect that.
Liberal Christians tend to rely on modern biblical scholarship rather than old translations which are faulty but conservatives feel that they are ‘truer’, because they don’t trust modern scholarship, particularly when it contradicts what they happen to believe (like homosexuality is a sin, abortion is a grave sin).
There’s a constant tug of war between those who want to move Christianity forward toward what they see as what Jesus intended, and those resist any change. That’s been true since the very beginning.