Theology and doctrine are not trivial matters. Yet there are people today who set aside biblical teaching and say, "I just want to experience God. I don't want to argue over doctrine. I just want to love Jesus." That is a nice sentiment, but it is also a very dangerous one. It means they might end up loving the wrong Jesus. They might end up believing the wrong doctrine.
That is why the Bible exhorts us again and again to have our lives and doctrine in order. As Paul instructed Timothy, "Take heed to yourself and to the doctrine. Continue in them, for in doing this you will save both yourself and those who hear you" (1 Timothy 4:16). One of the reasons that so many people are falling prey to false teachings today is because they do not have their doctrine in order.
I once heard a statistic that 80 percent of people who are pulled into various cult groups were once part of a church. That is not necessarily saying they were believers, but it is saying that these people had some church involvement at some point in their lives. If that statistic is correct, then it is alarming. It shows there are people who could have spent time in church, maybe a lot of time, but because they didn't have their doctrine in order, they were led down the wrong road.
If you have your doctrine in order, if you know what the Bible teaches, then you will be able to refute false teaching and defend your faith. It's what Jude means by exhorting Christians to "contend earnestly for the faith which was once for all delivered to the saints" (Jude 1:4).