Contradiction with James 4:13-15
Acts 18:21 expresses Paul’s determination to return to Jerusalem if God wills, while James instructs believers to acknowledge the Lord's will explicitly in their plans, suggesting a more cautious approach to making future plans.
James 4:13-15: Go to now, ye that say, To day or to morrow we will go into such a city, and continue there a year, and buy and sell, and get gain:
Contradiction with Proverbs 27:1
Acts 18:21 reflects Paul’s confident commitment to return, assuming divine permission, while Proverbs advises against boasting about tomorrow, emphasizing the uncertainty of future plans.
Proverbs 27:1: Boast not thyself of to morrow; for thou knowest not what a day may bring forth. [to...: Heb. to morrow day]
Contradiction with Matthew 5:37
Acts 18:21 involves Paul making a conditional promise, potentially contradicting Jesus’ teaching in Matthew to let "your communication be, Yea, yea; Nay, nay," which encourages straightforwardness without conditional clauses.
Matthew 5:37: But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil.
Contradiction with Matthew 6:34
Acts 18:21 implies looking ahead and planning for the future contingent upon God's will, whereas Matthew advises against worrying about the future, suggesting faith in God's provision for each day.
Matthew 6:34: Take therefore no thought for the morrow: for the morrow shall take thought for the things of itself. Sufficient unto the day [is] the evil thereof.