Take God at His Word.

1 John 2:12
It is evident, therefore, that if you TAKE GOD AT HIS WORD, your sins, however many, “Are FORGIVEN.”―See 1 John 2:12.
CHRIST JESUS, as Son of man, having “once” settled, with His own life’s blood, the question of sin, the reader is entreated to see whether he has settled the question of his own soul’s salvation by “only” (Mark 5:36) believing the record that God has given of His Son (see 1 John 5:11),1 and then letting his life, words, and habits show to all that Christ is in his heart, not only “the” (Colossians 1:27) hope of glory, but the certainty of acceptance with God.
 
1. “And this is the record, that God hath given to us eternal life, and this life is in His Son.”