Hebrews 3:14

For we are made partakers of Christ
Being loved by him, given to him, and chosen in him before the foundation of the world; and so participate of all spiritual blessings in him; for this respects something past, and may be rendered, "we have been made". The phrase is expressive of union to Christ, which is not by faith on man's part, and by the Spirit on Christ's part, but by his everlasting love, taking his people into an oneness with himself; thereby becoming their head, surety, and representative, which is the ground and foundation of all the blessings of grace being imparted to them: hence arises communion; as this is a conjugal union, there is communion of names, of persons, of goods, of honour and dignity, and of everlasting glory; as it is a federal or representative union, hence a non-imputation of sin, justification, and freedom from condemnation; and as it is an union of head and members; hence a communication of life, and the security of it, and of all grace and strength; hence holiness, fruitfulness, and perseverance, and everlasting happiness both of soul and body:

if we hold fast the beginning of our confidence steadfast unto the
end;
by "confidence" is meant faith, which is an hypostasis, or subsistence, which is the word here used; and is so called, because it gives a kind of subsistence, substance, or being, to things it is concerned with, ( Hebrews 11:1 ) and because it is a great support to believers, under their various exercises; and is that by which they have an open, spiritual, and comfortable subsistence, and abiding in Christ: the "beginning" of it, which is to be held fast, is either Christ himself, who is the (arch) , "the beginning", the author, and finisher of faith; and so this shows from whom, and in what way, this grace is distributed; and is expressive of communion with Christ, and is an evidence of the participation of him: or else the Gospel, which is the means of implanting faith, and directs to that which is the ground and foundation of it; and this is to be held fast, and never to be departed from: or else the grace of faith itself, which is a grace but begun, not yet finished, but shall continue, and is to be held fast, and constantly exercised; and perseverance in believing on Christ is an evidence of union to him.