Paying a Full Tithe Is an Essential Part of Our Worthiness

Doctrine and Covenants 119:5–7 

5 Verily I say unto you, it shall come to pass that all those who gather unto the land of Zion shall be tithed of their surplus properties, and shall observe this law, or they shall not be found worthy to abide among you.
6 And I say unto you, if my people observe not this law, to keep it holy, and by this law sanctify the land of Zion unto me, that my statutes and my judgments may be kept thereon, that it may be most holy, behold, verily I say unto you, it shall not be a land of Zion unto you.
7 And this shall be an ensample unto all the stakes of Zion. Even so. Amen.

Elder John Wells said:

“Tithing is a fundamental principle of the gospel of Jesus Christ. To those who observe it fully there comes a deeper love of the gospel. It is just as essential to our growth and development in this Church as are repentance, baptism, or any other fundamental laws. It will develop in men and women a deeper devotion to the truth and greater willingness to serve their fellowmen; and, above all, it will increase their testimony of the gospel.”

(In Conference Report, Apr. 1926, 121.)