Saint Paul wrote in the letter to the Romans (8:24) that “we are saved by hope.” Hope is one of the three theological virtues, along with faith and love (1 Corinthians 13:13).
To assume, or worse, to presume that God will save us no matter what discards the virtue of hope, and renders void Christ’s admonition to persevere to the end so as to be saved (Matthew 10:22, 24:13, Mark 13:13), and Paul’s admonition to run the race so as to win (1 Corinthians 9:24). It also violates Paul’s teaching in Romans 11:22, that we can be cut off from the vine.
As well, why did Paul have a ministry of reconciliation (2 Corinthians 5:18), admonishing Christians to be reconciled with God (2 Corinthians 5:20)?
The answer is post-baptismal sin. This is the elephant in the bible Christian’s living room. Christ opened the gates of heaven for us. He does not carry us through those gates. We must do that ourselves by persevering to the end, by running the race so as to win, by holding fast to our hope and by being reconciled to God for our post-baptismal sin.