“God is faithful, by whom ye were called unto the fellowship of his Son Jesus Christ our Lord.”
King James Version (KJV)
1:9 God is faithful - To all his promises; and therefore to him that hath shall be given. By whom ye are called - A pledge of his willingness to save you unto the uttermost.
1Co 1:9 God [is] faithful. Hence he will faithfully discharge his part of the covenant. His promises may be relied upon. By whom ye were called, etc. The fact that he had called the saints to fellowship with his Son, is proof that their salvation will be completed.