What are the differences and similarities between free grace salvation and decisionism? I don't even know what these mean.
The scriptures tell us that every man and woman is born into this world as an enemy of God because we sin. We are rebellious, enemies and disobedient towards God,
But God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us. Much more then, having now been justified by His blood, we shall be saved from the wrath of God through Him. For if while we were enemies, we were reconciled to God through the death of His Son, much more, having been reconciled, we shall be saved by His life. (NASB) Romans 5:8-10
For just as you once were disobedient to God, but now have been shown mercy . . . (NASB) Romans 11:30
I John 3:4 says sin is lawlessness. So God had to do something to rescue us from spiritual death – living forever in the Lake of Fire. We were in trouble and on our way to eternal torment.
So what did God do? He sent Jesus to die a physical death in our place so that we could live eternally with Him. All that is required of us is to place our trust, that is depend, on Jesus to forgive our sins. In the Greek, the terms “believe, trust, depend, confidence, faith, conviction, entrust, abandonment, and persuade” all come from the same Greek word PISTIS. They are interchangeable words and concepts. If we say we believe in Jesus, we are saying we are trusting in Jesus, we have been persuaded, or we have abandoned ourselves to Jesus for the forgiveness of our sins. That is all that God requires because there is nothing you can do to deserve eternal life with God,
ALL HAVE TURNED ASIDE, TOGETHER THEY HAVE BECOME USELESS; THERE IS NONE WHO DOES GOOD, THERE IS NOT EVEN ONE. (NASB) Romans 3:12
Free Grace Salvation
So God provides salvation as a free gift to those who believe in Jesus – nothing else is required. He does this because He loves us. The word grace refers to this love – love we do not deserve – “undeserved love,”
For by grace you have been saved through faith; and that not of yourselves, it is the gift of God; not as a result of works, that no one should boast. (NASB) Ephesians 2:8-9
This is “free grace salvation.” There is nothing else required and there is nothing else we could have done. We receive this “free grace” when we rely on Jesus for the forgiveness of our sins. Did you notice that this faith is a gift from God?
Some in the free grace movement have said a person can be saved by intellectual assent to the facts about Christ. Those who teach and preach this idea have missed the mark. Biblical salvation is not a mental assent to facts about Jesus. Even the demons know the facts, and they do believe Jesus is God and the Savior of the world. The scriptures teach that a person is forgiven of his sins the moment he recognizes his own sinfulness, sees his need for forgiveness, believes on Jesus, depends on Jesus, trusts in Jesus, entrusts himself to Jesus, or abandons himself to Jesus and Jesus alone for the forgiveness of his sins. This is the biblical faith God gives as a gift.
Decisionism is a unique term that says a person can become a Christian by signing a card, raising their hand, or walking an aisle at church to become a Christian. The basic idea is the person is not really entrusting themselves to Jesus for the forgiveness of their sins. That is, there is nothing beyond intellectual assent. There is no sense in which they are trusting or depending on Christ. Decisionism means the person is merely saying, “I believe” and that is all there is.
God calls us to believe while causing us to believe in Jesus Christ. By His grace He gives us a free gift of faith – the mark our sins are forgiven.