The letter to the Colossians presents us with a good example of the warning here. The church members had been presented with something that looked attractive, something they were told would enhance their worship of God, but it was actually a pagan idea. Contrary to the sales pitch they were hearing, they needed to get it out of their lives, out of their worship of God, or it would eventually lead them completely astray.
They were being deceived by something that appeared right. It seemed so good, and it indeed had its positive qualities, in a way. Paul, though, could see that death waited at its end. The people, apparently, were deluded into thinking about it an entirely different way.
Humanly, God has given us multiple ways to express our personalities that have nothing at all to do with sin or necessarily, with His way. But there is only one "Way," and that is His. When it is alloyed with other ways, it is not improved by any means. The Word of God is pure, and when things are added to it, it is not made stronger or enhanced. Added things actually make it worse; it is made weaker.
We can express our personalities in things like fashion. Look how many different designs there are to clothing. The same applies to furniture or automobiles. Their makers change them on us every so often to make them appeal. People buy things that appeal to the expression of their personalities. The same is true with houses and yards. Look at the landscaping varieties that there are—hundreds of different flowers, bushes, and trees that we can put in our yards to express a little bit of the beauty of God in our own way. Food and drink are other examples of variety in personal expression.
But in terms of morality and spirituality, the Way is extremely narrow. "Wide is the gate and broad is the way that leads to destruction, . . . [yet] narrow is the gate and difficult is the way way which leads to life, and there are few who find it" (Matthew 7:13-14). This is the principle we are dealing with in this case. In Colosse, the Christians were victims of yet another attempt to syncretize something moral and spiritual—but humanly devised—to God's Way.
In this case, it was a philosophy of asceticism and the worship of demons, which they were being told would enhance their worship of God. It appeared to be so spiritual, but it was effectively cutting them off from the true Object of their faith and their Source of power to overcome—Christ.