Wherefore let him that thinketh he standeth take heed lest he fall.
Thinketh he standeth - namely, "by faith;" in contrast to 1 Corinthians 10:5 (Romans 11:20).
Fall - from his place in the Church (cf. 1 Corinthians 10:8, "fell"), both temporally and spiritually (Romans 14:4). Our security as relates to God consists in faith; as relates to ourselves, in fear.