OK, let's unpack your statement here. To be clear, the Bible promises that anyone who believes is saved eternally. Do you agree or not? That is the only issue. Period.
Do you accept or reject Rom 8:38-39? Because it answers your concerns.
38For I am convinced that neither death, nor life, nor angels, nor principalities, nor things present, nor things to come, nor powers, 39nor height, nor depth, nor any other created thing, will be able to separate us from the love of God, which is in Christ Jesus our Lord.
I bolded 2 things to help you understand the infinite grace of God: the present and the future. Paul is here saying that regardless of what comes (future), believers will not be separated from the love of Christ. Period.
Just answer my questions, please.