Matthew 13:20-21 But he that received the seed into stony places, the same is he that heareth the word, and anon with joy receiveth it; Yet hath he not root in himself, but dureth for a while: for when tribulation or persecution ariseth because of the word, by and by he is offended.
2 Timothy 3:12 Yea, and all that will live godly in Christ Jesus shall suffer persecution.
Matthew Henry:
Impressions that are not deep, will not be durable, but will wear off in suffering, trying times; like footsteps on the sand of the sea, which are gone the next high tide of persecution; when that iniquity doth abound, the love of many to the ways of God waxeth cold; many that keep their profession in fair days, lose it in a storm; and do as those that go to sea only for pleasure, come back again when the wind arises.