Charles Spurgeon Commentary Luke 13:24

"Strive to enter in by the narrow door: for many, I say unto you, shall seek to enter in, and shall not be able." — Luke 13:24 (ASV)

For many, say to you, will seek to enter in, and shall not be able.

They will only seek, not strive, to enter in. There will also come, in the future, a time when they may seek as they will, and strive as they will, to enter in, but it will be too late then. Once having passed into another world, there will be no hope for any seeker or striver.