Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness? 2 Corinthians 6:14. OHC 257.1
I would warn you*Counsel to a young woman. to be guarded as to where you bestow your affections.... Remember that your life belongs to Jesus, and that you are not to live for yourself alone. You are not to enter into the marriage relation with an unbeliever; for in so doing, you do exactly contrary to that which Jesus has commanded. Shun those who are irreverent. Shun one who is a lover of idleness; shun the one who is a scoffer of hallowed things. Avoid the society of one who uses profane language, or is addicted to the use of even one glass of liquor. Listen not to the proposals of a man who has no realization of his responsibility to God. OHC 257.2
The pure truth, which sanctifies the soul, will give you courage to cut yourself loose from the most pleasing acquaintance whom you know does not love and fear God, and knows nothing of the principles of true righteousness. We may always bear with a friend's infirmities and with his ignorance, but never with his vices. Never marry an unbeliever. OHC 257.3
I am only voicing to you the word of God, for He declares that such a union will result in drawing away your heart from loving and serving Him.... As a child of God, you are permitted to contract marriage only in the Lord.... Should you consent to unite your life with that of an unbeliever, you would be disregarding the Word of God and imperiling your soul.... OHC 257.4
Your life is too precious a thing to be treated as of little worth. Calvary testifies to you the value of your soul.16Letter 51, 1894. OHC 257.5
Let every step toward a marriage alliance be characterized by modesty, simplicity, sincerity, and an earnest purpose to please and honor God. Marriage affects the afterlife both in this world and in the world to come. A sincere Christian will make no plans that God cannot approve.... Make Christ your counselor. Study His word with prayer.17The Ministry of Healing, 359. OHC 257.6