KJV:
Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?
NASB:
Test yourselves to see if you are in the faith; examine yourselves! Or do you not recognize this about yourselves, that Jesus Christ is in you-- unless indeed you fail the test?
KJV:
Which is come unto you, as it is in all the world; and bringeth forth fruit, as it doth also in you, since the day ye heard of it, and knew the grace of God in truth:
NASB:
which has come to you, just as in all the world also it is constantly bearing fruit and increasing, even as it has been doing in you also since the day you heard of it and understood the grace of God in truth;
KJV:
Forbidding to marry, and commanding to abstain from meats, which God hath created to be received with thanksgiving of them which believe and know the truth.
NASB:
men who forbid marriage and advocate abstaining from foods which God has created to be gratefully shared in by those who believe and know the truth.
KJV:
For it had been better for them not to have known the way of righteousness, than, after they have known it, to turn from the holy commandment delivered unto them.
NASB:
For it would be better for them not to have known the way of righteousness, than having known it, to turn away from the holy commandment handed on to them.