Mark 1:14,15
Now after that John was put in prison, Jesus came into Galilee, preaching the gospel of the kingdom of God,
and saying, “The time is fulfilled, and the Kingdom of God is at hand. Repent ye and believe the Gospel.”
Jesus commanded people to do something, in fact two things: (1) repent (2) believe the gospel.
Romans 10:9,10
that if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.
Yes, we are saved purely by grace, not by works, but this does not mean we have no conditions to meet. We must confess and believe. That is not working for salvation, that is choosing to comply with a required condition.
We do not suddenly get zapped by God into salvation, without us hearing and responding to the gospel.
Ephesians 2:8,9
For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:
Not of works, lest any man should boast.
Romans 10:17
So then faith cometh by hearing, and hearing by the word of God.