If the Old Testament commands something, does that mean Christians still have to do it?
No. Just because the Old Testament told Israel to do something does not mean it remains valid for Christians today. For example, animal sacrifices are not required; believers are not under that system. Old Testament commands must be shaken up, because what applied to Israel does not automatically apply to us.
Les teaches that an Old Testament command given to Israel does not automatically remain valid for believers today. He illustrates this with animal sacrifice: if the Bible says to bring an animal sacrifice, you do not go out and buy a lamb. We are not under that today; we know better. This principle carries through everything—just because the Old Testament told Israel to do something, that does not mean it is still valid for us today, so we have to shake these things up. He then moves to Paul's teaching on giving. Paul says he does not speak by commandment, but by the zealousness of others, to prove the sincerity of their love. Les notes that even when Paul says he is not writing by commandment, it is still the inspired Word of God because the Holy Spirit prompted him to write it. So while Old Testament commands to Israel are not automatically binding, Paul's writings carry divine authority.