According to 'once saved always saved' doctrine he's not even saved to begin with. He left.
According to those who reject the true gospel of the eternal assurance of the believer from what I have read here we have multiple redefinition of words.
-Saved does not mean saved, it is temporal, it means you better keep believing and then you may be saved based on your ability to have kept that belief
-Redeemed, is yes, maybe, sometimes, depending how well one trusts and has faith in the blood of Christ on a moment by moment basis, because no one really knows how much faith/belief one needs to be redeemed over the course of a lifetime
-Justification is quasi-justification because apparently the blood of the cross is a give and take proposition, a quasi bi-lateral agreement where God is allowed to renege on his promises according to the failures of his subjects
-Quasi-justification must be maintained by ongoing belief because obviously the failures of the first covenant were not enough, and God was not able to create a new agreement/covenant where He can assume all the debt and secure the once and for all innocence of his debtors who agree to enter into the agreement.
God is just incompetent that way, therefore He needs us to do our part to maintain our justification, even though we will fail, but our pride tells now we will not, we will we keep the faith to meets God's standard even though no one really knows how much faith will keep us saved.
-Sanctification and the indwelling of the Spirit of God are temporaral based on our performance because God has no ability to work in the life of the believer to chasten or recover
And last but not least, faith/belief, no longer a singular event which brings justification, positional sanctification, redemption and promised glorification.
If belief as defined by scripture is not a singular event that brings the permanent and secure promises, actions and declarations of God in the life of the new believer, then all of the above is absolutely correct so really one is on one's own working to secure one's salvation.
If salvation is not secure then one has to work/achieve it and that is not the gospel. You can twist and turn all you want but you have made ongoing belief a work since it requires sustained effort on the part of the person which is a work for the payment of eternal life
Which tells me that you have not come to understand that God places the believer in a different relationship with Himself based one act of faith in the finished work of the cross, what we do after regeneration is from a place of freedom and love not compulsion to achieve salvation.