The devil likes to work gradually to twist our minds; we often do not know he is doing it, and that is exactly what he wants. He did it years ago with Roe v Wade, and he was able to make large numbers of people think that it is a good thing to murder innocent babies. Those same people, likely in another context, would not accept that lie, but because they were fed that poison slowly over time, they fell into it without realizing. This is likely because they were not paying attention to their own minds; which is much more common that you might think.
We are told many times in Scripture to be discerning and warned that we should never "trust our own understanding" of things (even of God's word!). Yet, because we are "inside" our own heads, we often do not see the subtle changes the evil onminde accomplishes in us. He finds various ways to catechize us, and all too often we accept it without question. Today, the devil will often use things that we accept passively (though we should not do so!), like movies, music, and other entertainments.
He does this incremental procedure with every one of us, and if we are not being critical in our examination of our own thoughts, words, and deeds, then we will fall for his lies. He will usually push and stretch us on a small issue, then a bigger one, etc., until we have compromised and fallen for something that we would have rejected outright not long before. Are you doing a serious self-examination of your ideas and beliefs? We cannot imagine that we are fine just because we did not kill anyone last week. Even the scrupulous person can miss subtle changes in thinking.
Let us not be like the world who follows the devil blindly. Let us test our thoughts according to the testimony of the Church, and the Scriptures. Let us be willing to be found wrong, and be ready to repent and change our minds if we find that we have been deceived. Let us love God with heart, soul, mind, and body.