Paul writes this verse in Philippians. Hold true. The definition of the Greek word for "hold true" means to walk in line. This makes me think back to elementary school when mastering the art of walking in line was a necessity. Every child found that looking around or not paying attention would just cause you to run into the kid in front of you, trip or stumble, & then that usually brought on a need for a teacher to institute a silent single-file line. Proven to be the most successful way of walking in line: keep your eyes on the person you are following. So to hold true to what we know, we must keep our eyes on Jesus.
It's easy for other things to sound right. Fair. Just. It's easy for someone to plead their case & make us believe, make us want to follow their way of thinking. But the only way is His way. The only Truth is what is found in the Word of God. No way of thinking trumps the Gospel. These words are just as relevant now as when Paul wrote them. Just because we live in a different world does not mean God's words don't apply. Hold true to what you know is Truth.