Mormons must remain worthy and obedient to the required LDS Celestial covenants and laws their entire lives to have any assurance of becoming gods in the highest Celestial kingdom. Individual Mormons must endure and remain fully worthy until the end, even beyond death in paradise.
How do Latter-day Saints remain worthy Mormons? Besides personal holiness and several other covenant obligations, two of the central requirements are that they obey the Law of Tithing and follow the requirements of Joseph Smith's Word of Wisdom revelation.
The Law of Tithing
The payment of a full tithe, usually understood as 10 percent of one's gross income by most Mormons, is expected of worthy Mormons and is necessary to progress into godhood. For Mormons, the Law of Tithing is the law of eternal inheritance. Mormons can jeopardize their inheritance in the Celestial kingdom if he or she failed to tithe in full.
It is understood within the LDS Church that a person who obeys or disobeys the Law of Tithing reveals whether he or she is truly for the kingdom of God or against it. Every year each Mormon has a "tithing settlement" meeting with the ward bishop to ensure that he or she has paid the full tithe. If not, the person will be admonished and the salvation consequences will be explained. Although Mormons are not excommunicated for not tithing in full, they are excluded from holding major leadership roles and from having access to the temple ordinances.
Obeying the Word of Wisdom Revelation
Obedience to Joseph Smith's Word of Wisdom revelation recorded in Doctrine and Covenants section 89 is an essential requirement of Mormon worthiness. To remain a worthy Mormon, the person must totally abstain from wine, alcoholic drinks, tobacco, coffee, and tea.
Reading the historical context that motivated Smith's Word of Wisdom revelation is very interesting, insightful, and even odd, especially since the LDS Church emphasizes that our position in eternity is dependent on this revelation's complete obedience. This is the history given by the official LDS student manual on Doctrine and Covenants section 89:
The first school of the prophets was held in a small room situated over the Prophet Joseph's kitchen, in a house which belonged to Bishop Whitney. The brethren came to that place from hundreds of miles to attend school in a little room probably no larger than eleven by fourteen. When they assembled together in this room after breakfast, the first thing they did was to light their pipes and, while smoking, talk about the great things of the kingdom and spit all over the room, and as soon as the pipe was out of their mouths a large chew of tobacco would then be taken. Often when the Prophet entered the room to give the school instructions he would find himself in a cloud of tobacco smoke. This, and the complaints of his wife having to clean so filthy a floor, made the Prophet think upon the matter, and he inquired of the Lord relating to the conduct of the Elders in using tobacco, and the revelation known as the Word of Wisdom was the result of his inquiry.
Our human righteousness-no matter how heroic it might be-falls short of the glory of God. Biblical salvation is righteousness, peace, and joy in the Holy Spirit, based on the following truths: "For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord" (Rom. 6:23); "For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast" (Eph. 2:8-9).
In celebration of the saving gift of eternal life in Jesus Christ, here it is concluded with the apostle Paul's declaration found in Romans 8:31-39, for it seems to sum everything up:
What then shall we say to these things? If God is for us, who can be against us? He who did not spare his own Son but gave him up for us all, how will he not also with him graciously give us all things? Who shall bring any charge against God's elect? It is God who justifies. Who is to condemn? Christ Jesus is the one who died-more than that, who was raised-who is at the right hand of God, who indeed is interceding for us. Who shall separate us from the love of Christ? Shall tribulation, or distress, or persecution, or famine, or nakedness, or danger, or sword? As it is written, "For your sake we are being killed all the day long; we are regarded as sheep to be slaughtered." No, in all these things we are more than conquerors through him who loved us. For I am sure that neither death nor life, nor angels nor rulers, nor things present nor things to come, nor powers, nor height nor depth, nor anything else in all creation, will be able to separate us from the love of God in Christ Jesus our Lord.