FAQ:Who are Gods elect?
Romans 8:28-31 KJV  And we know that all things work together for good to them that love God, to them who are the called according to his purpose.  For whom he did foreknow, he also did predestinate to be conformed to the image of his Son, that he might be the firstborn among many brethren.  Moreover whom he did predestinate, them he also called: and whom he called, them he also justified: and whom he justified, them he also glorified.  What shall we then say to these things? If God be for us, who can be against us?
So it's clear from scripture that there are those who are foreknown by God.
I interpret this as that since God the Father can know things before they happen he can foreknow who will come to faith in his Son in their lifetime.
Romans 8:32-33 KJV  He that spared not his own Son, but delivered him up for us all, how shall he not with him also freely give us all things?  Who shall lay any thing to the charge of God's elect? It is God that justifieth.
So Gods elect are believers.