Maybe it would be more accurate to say they use their misinterpretation of scripture, to support their non scriptural beliefs.
The Bible is VERY clear, that we can have assurance of salvation. Many of them probably think we are committing the sin of presumption by having assurance of salvation. Oh well, such is life. That's one sin I don't mind committing. 😀😆😄
In fact, didn't John tell us "but these have been written so that you may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name." John 20:31
14“As Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up; 15so that whoever believes will in Him have eternal life. John 3:14-15
24“Truly, truly, I say to you, he who hears My word, and believes Him who sent Me, has eternal life, and does not come into judgment, but has passed out of death into life.John 5:24
13These things I have written to you who believe in the name of the Son of God, so that you may know that you have eternal life. 1 John 5:13
Paul noted this assurance also:
13In Him, you also, after listening to the message of truth, the gospel of your salvation—having also believed, you were sealed in Him with the Holy Spirit of promise, 14who is given as a pledge of our inheritance, with a view to the redemption of God’s own possession, to the praise of His glory. Ephesian 1:13-14
Sure seems like He wanted us to have the assurance of our salvation.