Joseph Smith taught,

“Let us here observe, that a religion that does not require the sacrifice of all things never has power sufficient to produce the faith necessary unto life and salvation; for, from the first existence of man, the faith necessary unto the enjoyment of life and salvation never could be obtained without the sacrifice of all earthly things. It was through this sacrifice, and this only, that God has ordained that men should enjoy eternal life; and it is through the medium of the sacrifice of all earthly things that men do actually know that they are doing the things that are well pleasing in the sight of God. When a man has offered in sacrifice all that he has for the truth’s sake, not even withholding his life, and believing before God that he has been called to make this sacrifice because he seeks to do his will, he does know, must assuredly, that God does and will accept his sacrifice and offering, and that he has not, nor will not seek his face in vain. Under these circumstances, then, he can obtain the faith necessary for him to lay hold on eternal life.”

Joseph Smith, Lectures on Faith 6:7