Charles Spurgeon Commentary Ephesians 4:20-25

"But ye did not so learn Christ; if so be that ye heard him, and were taught in him, even as truth is in Jesus: that ye put away, as concerning your former manner of life, the old man, that waxeth corrupt after the lusts of deceit; and that ye be renewed in the spirit of your mind, and put on the new man, that after God hath been created in righteousness and holiness of truth. Wherefore, putting away falsehood, speak ye truth each one with his neighbor: for we are members one of another." — Ephesians 4:20-25 (ASV)

But you have not so learned Christ; if indeed you have heard him, and have been taught by him, as the truth is in Jesus: that you put off concerning your former way of life the old man, which is corrupt according to the deceitful lusts; and be renewed in the spirit of your mind; and that you put on the new man, which according to God is created in righteousness and true holiness. Therefore, putting away lying, let everyone speak truth with his neighbor: for we are members one of another.

Those who lie in jest will find out that God counts it as sinning in earnest. Let us never attempt to deceive. In the East, in ancient times, and I might say as much of the present day, it was not usually considered a great sin to lie; the great evil was when the liars were found out. Oh! but the Christian man must be true in every word that he speaks; he must faithfully keep his promises and be known to be a trustworthy, reliable man. If you are not true, Christ will not acknowledge you as belonging to him.