Your one sin is worthy of eternal damnation by the perfect and Holy God who cannot and will not suffer your presence in His Kingdom.
Worst than that. When born, we still lack a human spirit regenerated in fellowship with God. That doesn’t happen until forgiveness, which occurs after we face Him and receive what He provided on the Cross. Children prior to the age of accountability and the mentally deficient never have the opportunity to face Him and consider the Gospel, so God is free to give them a regenerated spirit should they die physically and soulishly before they are given the opportunity to consider Him.
We are condemned first, before salvation.