ANSWER: Both forms are mandatory. All the requirements and prohibitions of the Decalogue, except the fifth, are in the indicative form, "Thou shalt" and "Thou shalt not." This is really in the Greek as strong as the imperative mood. Even though we had no expressed command, we would be bound to realize the highest ideal. This is found in the character of Jesus Christ. "While a better is in sight, we can rest in no good; and the refusal to move onward is to be a traitor to the highest, and so, finally, to the good itself," says Dr. Borden P. Bowne. Indifference in sight of spiritual perfection is a perilous attitude of a free moral agent professing faith in Christ.
— Steele's Answers pp. 108.