God is {h} faithful, by whom ye were called unto the fellowship of his Son Jesus Christ our Lord.

(h) True and constant, who not only calls us, but also gives to us the gift of perseverance.

People's New Testament

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.

Wesley's Notes

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.

Jamieson-Fausset-Brown Bible Commentary

9. faithful-to His promises (Php 1:6; 1Th 5:24).

called-according to His purpose (Ro 8:28).

unto . fellowship of . Jesus-to be fellow heirs with Christ (Ro 8:17-28), like Him sons of God and heirs of glory (Ro 8:30; 2Th 2:14; 1Pe 5:10; 1Jo 1:3). Chrysostom remarks that the name of Christ is oftener mentioned in this than in any other Epistle, the apostle designing thereby to draw them away from their party admiration of particular teachers to Christ alone.

Matthew Henry's Concise Commentary

1:1-9 All Christians are by baptism dedicated and devoted to Christ, and are under strict obligations to be holy. But in the true church of God are all who are sanctified in Christ Jesus, called to be saints, and who call upon him as God manifest in the flesh, for all the blessings of salvation; who acknowledge and obey him as their Lord, and as Lord of all; it includes no other persons. Christians are distinguished from the profane and atheists, that they dare not live without prayer; and they are distinguished from Jews and pagans, that they call on the name of Christ. Observe how often in these verses the apostle repeats the words, Our Lord Jesus Christ. He feared not to make too frequent or too honourable mention of him. To all who called upon Christ, the apostle gave his usual salutation, desiring, in their behalf, the pardoning mercy, sanctifying grace, and comforting peace of God, through Jesus Christ. Sinners can have no peace with God, nor any from him, but through Christ. He gives thanks for their conversion to the faith of Christ; that grace was given them by Jesus Christ. They had been enriched by him with all spiritual gifts. He speaks of utterance and knowledge. And where God has given these two gifts, he has given great power for usefulness. These were gifts of the Holy Ghost, by which God bore witness to the apostles. Those that wait for the coming of our Lord Jesus Christ, will be kept by him to the end; and those that are so, will be blameless in the day of Christ, made so by rich and free grace. How glorious are the hopes of such a privilege; to be kept by the power of Christ, from the power of our corruptions and Satan's temptations!