God saves all kinds of sinners. One’s theology does not necessarily exclude one from this grace. For example, many people are in a sanctifying state. They are a theological work in progress. A child who is elect may not have their theology down pat. If this child dies earlier than time allows for the child to have all his jots and tittles aligned by the Holy Spirit, the Lord considers that. If this child were to live to a ripe age, rejecting the truths of scripture emphatically, it is quite possible that this adult was never elect, nor regenerated at all and is probably not a recipient of God’s grace and mercy as the Holy Spirit will lead the elect into all truth.
No one enters Heaven with a disjointed theology-upon death, Christ perfects and straightens out crooked things, for His glory alone.