I’ve got to say I am constantly meeting people who think they can work hard enough and long enough so that God will save them. I used to be one of those thinkers.
The concept that we are saved by grace is completely opposed to the concept that our own personal efforts enable us to meet the requirements of a holy God. It is in the nature of every person alive to think that they can do something to better themselves, to make themselves more acceptable to God, but this isn’t how it works. This thinking is opposed to God's thinking.
God, and God only, can save us. He saves us by His enormous grace that was shown to us in the birth, death and resurrection of His only Son. God reached down to the earth to bring us closer to Him. We, on the earth, can’t do a single thing to merit Him saving us. No amount of effort from us in studies, doctrinal purity, prayers, meditations, charity work, mission work, evangelising or witnessing can make us holy. Only God can make us holy.
I love this section of scripture that spells it out so clearly:
3 Once we, too, were foolish and disobedient. We were misled and became slaves to many lusts and pleasures. Our lives were full of evil and envy, and we hated each other. 4 But—
When God our Saviour revealed his kindness and love, 5 he saved us, not because of the righteous things we had done, but because of his mercy. He washed away our sins, giving us a new birth and new life through the Holy Spirit. 6 He generously poured out the Spirit upon us through Jesus Christ our Saviour. 7 Because of his grace he made us right in his sight and gave us confidence that we will inherit eternal life (Tit. 3:3-7).
See the process? We were hopeless sinners until God extended to us His kindness and saved us. Any righteous deeds that we did weren’t enough to save us. God washed away our sins. God made us anew and God poured His Holy Spirit into us to help us live lives that would please Him. End of story! It is all about God doing it in us.
Paul says in another place that we were justified by faith and that we then had peace with God though our Lord Jesus Christ. He adds that the love of God was poured out into our hearts by the Holy Spirit (Rom. 5:1-5 generally).
All we did was give up the idea that we can do anything to save ourselves and believe in Jesus and then He did the rest. Not our beliefs, or good behaviours or obedience to rules. God saved us.
This is the gospel --- the righteousness of God from faith to faith (Rom. 1:16-17). Faith first and faith last.
For it is by believing in your heart that you are made right with God, and it is by openly declaring your faith that you are saved (Rom 10:10).
All quotations are from the NLT.