Satan uses lies and disinformation to promote self-satisfaction over obedience to God. The way to the kingdom is through self-denial, even suffering unjustly.
How are we different from those who have fallen away from the truth? How do we know that we will not also follow a path of deception and eventual apostasy?
As Moses had to veil his luminous face, so, metaphorically, the God of this age mercifully blinds carnal individual for now because light hurts their eyes.
Outcome based religion exalts numerical growth and feeling good over the truth of God, promoting the use of modern psychology over 'divisive' biblical doctrine.
It is easy to denigrate a matter as not being 'salvational,' but the real question to ask is, How will this action affect my relationship with God?
Under both the Old and New Covenants, refusal to keep to keep God's Law severs the relationship. God's law protects us and brings us quality life.
Christ endured many more than three temptations; rather, He was tested continuously, and perhaps the intensity increased as He neared the end of His life.