Luke 8:13

Which for a while believe

(ο προς καιρον πιστευουσιν). Ostensibly they are sincere and have made a real start in the life of faith.They fall away

(αφισταντα). Present middle indicative. They stand off, lose interest, stop coming to church, drop out of sight. It is positively amazing the number of new church members who "stumble" as Mark 4:17 has it (σκανδαλιζοντα), do not like the pastor, take offence at something said or done by somebody, object to the appeals for money, feel slighted. The "season of trial" becomes a "season of temptation" (εν καιρω πειρασμου) for these superficial, emotional people who have to be periodically rounded up if kept within the fold.