Once saved, always saved is not a doctrine found in the Bible.
Even Paul acknowledged that he himself could possibly fall away. (1 Corinthians 9:27).
Salvation is dependent upon understanding, believing and obeying the gospel preached by Jesus Christ and his apostles. To begin, we must believe that the scriptures which make up the Bible were given by the inspiration of God and are inerrant except for minor errors of transcription and translation. The scriptures themselves are written to make us ‘wise unto salvation’. (2 Timothy 3:15-17; 2 Peter 1:20)
We must first read the scriptures and understand the gospel for ourselves. When we understand the gospel we much repent of our sinful way of life – not just be sorry, but change the way that we live. Then we must be baptised into Jesus Christ by immersion in water for the remission of our past sins. (Acts 22:16)
After baptism we begin a new life. (Romans 6:4). Our new life is to be lived by the commandments of Jesus Christ. (John 15:13; Luke 6:46) Living by the commandments of Jesus Christ is described as walking in the light.
After baptism, we cannot live a sinless life, but providing we are making a determined effort to live by Christ’s commandments our sins will be forgiven by confession in prayer. (1 John 1:7-9) We are baptised into a body of like-minded believers and Jesus commanded us to meet ‘often’ to share bread and wine in remembrance of his sacrifice. This also serves as an opportunity to examine ourselves to see whether we are living by his commandments as Paul explains (1 Corinthians 11:23-29)
What makes our baptism valid is not who baptises us but what we believe when we are baptised. There are many ‘Christian’ denominations with different gospels. Most of them teach false doctrines based on the ideas of the Church ‘Fathers'. For example:
Thus, it is important to read the Bible and understand the gospel for ourselves.
The kingdom of God will be the restored kingdom of Israel in which Christ will rule the mortal population of the earth for 1000 years.
God promised Abraham, Isaac and Jacob an eternal inheritance on the earth which forms the basis of the gospel (Genesis 13:15). Eternal inheritance on the earth is the promise which those who believe and obey the gospel will also receive (Galatians 3:27-29; Romans 4:13)
As far as forgiveness for our sins is concerned, we are promised ongoing forgiveness when we are making an effort to live by Christ’s commandments. Ours is a merciful God who is not willing that any should perish – hence the parable of the prodigal son. It is never too late to believe and obey the gospel.
May I suggest that you read: Your Share in God’s Promises (please click on the title)
I hope you find this helpful.