I Can't Follow the Non-Muslims in Their Religious Matters, Right?

There's a dispute amongst our religion in this whole issue, which is something that is authentically mentioned in the Quran. There isn't Sahih evidence to point out that they... They did it. Even if it has been transmitted to us through a kabirah, a habirah, for example, it doesn't matter. We don't have fisheah in our religion that proves it or abrogates it. Also we don't have bottilu aidu sahu'an wa yam al-fiqh as some scholars say. And inshaar: I'm talking about customs, not talking about acts of worship,. But I can follow them