Whenever, they quote a bible verse stop them and read the context, often the context itself conradicts their proof text.
for example in an article in the Encylopedia of Mormonism called Book of Mormon, Biblical Prophecies about they quote Isaiah 29:4 “their speech would ‘whispher out of the dust’” as a prophecy for the book of mormon. If you read Isaiah 29 in context God is comdemming those who whisper out of the dust, thus cursing the Book of Mormon.
Isaiah 29
1Woe to Ariel, to Ariel, the city where David dwelt! add ye year to year; let them kill sacrifices.
2Yet I will distress Ariel, and there shall be heaviness and sorrow: and it shall be unto me as Ariel.
3And I will camp against thee round about, and will lay siege against thee with a mount, and I will raise forts against thee.
4And thou shalt be brought down, and shalt speak out of the ground, and thy speech shall be low out of the dust, and thy voice shall be, as of one that hath a familiar spirit, out of the ground, and thy speech shall whisper out of the dust.
5Moreover the multitude of thy strangers shall be like small dust, and the multitude of the terrible ones shall be as chaff that passeth away: yea, it shall be at an instant suddenly.
6Thou shalt be visited of the LORD of hosts with thunder, and with earthquake, and great noise, with storm and tempest, and the flame of devouring fire.
Leviticus 19:31
Regard not them that have familiar spirits, neither seek after wizards, to be defiled by them: I am the LORD your God.
Leviticus 20:6
And the soul that turneth after such as have familiar spirits, and after wizards, to go a whoring after them, I will even set my face against that soul, and will cut him off from among his people.
Leviticus 20:27
A man also or woman that hath a familiar spirit, or that is a wizard, shall surely be put to death: they shall stone them with stones: their blood shall be upon them.
Deuteronomy 18:11
Or a charmer, or a consulter with familiar spirits, or a wizard, or a necromancer.
Another text they like to quote is “there are gods many, and lords many” but, when you read the context,
1 Corinthians 8:4-6 (King James Version)
4As concerning therefore the eating of those things that are offered in sacrifice unto idols, we know that an idol is nothing in the world, and that *there is none other God but one. *
5For though there be that are called gods, whether in heaven or in earth, (as there be gods many, and lords many,)
6But* to us there is but one God, the Father*, of whom are all things, and we in him; and one Lord Jesus Christ, by whom are all things, and we by him.
When you confront them on polytheism, they will claim to be monotheist because they only relate to the 'god of this world’
2 Corinthians 4:4 (King James Version)
In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them.
read for context, you will refute most of their proof texts without much effort at alll