What is the love of the truth (2 Thessalonians 2:10)?

Yah (God) states in His word that people who do not love His TRUTH will receive STRONG delusion from Him.

"For the mystery of iniquity doth already work: only he who now letteth will let, until he be taken out of the way. And then shall that Wicked be revealed, whom the Lord shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming: Even him, whose coming is after the working of Satan with all power and signs and lying wonders, And with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved. And for this cause God shall send them strong delusion, that they should believe a lie: That they all might be damned who believed not the truth, but had pleasure in unrighteousness. But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth." (2 Thessalonians 2:7-13 KJV) 

So, Yah is saying that if a person does not love (Greek - agape: affection regarding) the truth, then he or she will be deceived.

The TRUTH is the instructions of Yah-the Torah and the Words of Yah (Psalm 119:142; John 17:17).

"More to be desired are they than gold, yea, than much fine gold: sweeter also than honey and the honeycomb." (Psalm 19:10)

"If ye then be risen with Christ, seek those things which are above, where Christ sitteth on the right hand of God. Set your affection on things above, not on things on the earth." (Colossians 3:1-2) 

A believer must learn to TREMBLE before Yah's words (Isaiah 66:2).