You can know for sure!
These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God. – I John 5:13
The only way is through Jesus Christ.
Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me. – John 14:6