“Work hard to enter the narrow door to God’s Kingdom, for many will try to enter but will fail." Luke 13:24
“His purpose was for the nations to seek after God and perhaps feel their way toward him and find him—though he is not far from any one of us. Acts 17:27
According to Matthew's account the narrow way was contrasted with a broad rode leading to destruction, which is considered relatively easy to get and stay on. Contrarily, effort needs to be expended to get on the narrow road, which leads to heaven. Our own pride, Satan, and the world make it a difficult task, but as Paul said in Acts, God sets things up so that people could find this way.
The key, I believe, is to accept the narrow way because it is God's way, the one He provides. One might say that the broad road is a combination of humanity's way to do it their way. Good works, memberships, achievements, all human activity may be commendable, but one must come to God on His terms. To invent a religion or formula, and being tolerant in views of what God wants from us, are only our version of what God wants -- they don't count.
People seek to make a connection with God, pitifully, using man-made materials. They "sew" a fabric, often large and eye catching, but it is a weak fabric which tears loose and doesn't connect us to God, no matter how impressive it looks. However, while acceptance through Christ is a small connecting thread, it is exceedingly strong. And we go through life that way, with a life dependent on a thread that is small but the only one that holds.
As the hymn implies, our hope is built on not only nothing less, but also nothing more, than Jesus' blood and righteousness.
My Hope Is Built On Nothing Less - Deborah Liv Johnson