First and foremost we must stick to the clear and unambiguous milk of His word when we run into passages that are a bit tough or unclear to us.
We will never, no not ever come into condemnation.
We will never perish.
We are born from imperishable seed.
Nothing can separate us from the love of Christ.
There are 100 plus very clear verses that tell us we have eternal life and we are 100% secure in Christ.
So yes, believers can and do fall away, go their own way and even deny Christ.
IMO, the idea of loss/forfeiting/walking away of salvation................IS falling away from Christ. Salvation is based upon His character and nature not ours.
He is patient with us. And full of Grace and mercy. But, he will discipline. He will deny us temporal blessing and possibly eternal blessings......And as noted by
@sawdust, We cannot even comprehend the ramifications of losing eternal blessings.
Most of us relegate Gods discipline to the likes of losing our grape sucker......It's a much bigger deal than that.....but it's not loss of salvation.