God never changes! Remember that.
The next time you are confronted with something from the Bible and these words cross your lips—"That was for back then; that isn't for us today," be very afraid, because you are treading on thin ice.
What you are saying is that you do not agree with what the Scriptures have said, what Jesus has said, and are thus trying to find a way to loose yourself from having to obey it. In this case, you are no better than an infidel.
Unless God Himself has changed something, unless it has been fulfilled in and by the person and work of Christ on the cross, unless there is an explicit "Thus says the Lord" command to alter or cancel something, then it still remains intact for you today.
You do not get to pick and choose what parts of Scripture you will obey. God is not interested in your opinions. Because our cultures are so vastly different, you need to understand biblical culture in order to understand a great deal of what was being said and what was meant by it. However, that does not make it relative only to biblical culture. You are under the same obligation to obey what the Scriptures command, whether your culture is identical or not with that of the biblical culture.
When the authors spoke or wrote, they did so under the inspiration of the Holy Spirit. Therefore, what has been written down comes directly from the heart and mouth of God Himself. God does not change. Therefore, what you desire to be only for a past culture is still incumbent upon you to practice and obey. If you do not understand something, seek to understand it. Do not simply sweep it under the rug in hopes you can ignore it and then claim ignorance when standing before the throne of judgment.
What Christ Jesus said in Scripture of His followers, He demands they obey. It was not said to the culture of that time with no application for our culture today. What He commanded and demanded of them back then, He still commands and demands from us today.
When it comes to God's Word and His instructions for us, never mouth the words, "That was for back then; that isn't for us today"!