Today we have so many different religions, belief systems and worldviews competing for our attention. Everyone seems to think they have got the best idea of how to live life. Or even more common these days is the idea that there is no right way to live at all and it's all about personal choice and personal truth. Tolerance these days is probably the most persuasive message out there. It says that all worldviews and claims to truth are equal. It sounds so reasonable and friendly but it's wrong! If there's any such thing as real objective truth at all then it has to be wrong.
John is convinced that there is plenty of real know-able objective truth about God and what he has said and done in our world, especially through his Son Jesus Christ. He also knows that there were so many other mixed messages and stories, ideas and claims to truth out there and he wanted his readers to know how to sort them out.
John says the bottom line is about what people say about who Jesus is. If they acknowledge that Jesus was and is the Son of God (a lot of implications for anyone who believes this!), then they can probably be trusted most of the time when they're talking about direction in life. But if they don't acknowledge Jesus was and is the Son of God (again a lot of implications here too!), then they can't be trusted on these crucial issues because they've ignored or rejected the most important intervention in human history that there's ever been - Jesus!
That's not too say that non-Christians don't ever have valuable things to say. I've learned many wise things from non-Christians. It just means we shouldn't allow non-Christians to convince us about why and how we live for God because he must be the final authority.
It also doesn't mean that Christian teachers don't ever get it wrong. I've heard preachers say the most stupid things over the years. It just means that if someone has accepted Jesus as the Son of God and their own saviour and rescuer, then they can probably be trusted on big matters like why and how to live for God because they're following him too.
In short, we need to measure up all big ideas with what God says in the Bible (the written word of God) and with the live of Jesus (the living word of God) if we want to be sure about them one way or the other.
In the assembly we looked at how to spot fakes. We saw that although there are many tests we can do to spot if a bank note is a fake, the best way by far is to handle real money as much as possible. Then when a fake note comes along, we'll spot it a mile off. This is true in life too. If we want to avoid being taken in by convincing fakes, we must be familiar with the real truth as much as we can. This means knowing God for ourselves, listening to him by reading the Bible, speaking to him in prayer and trusting in him.