An
apparent contradiction, perhaps, but only by ignoring the monergistic work of God in bringing about a person's salvation.
Salvation begins with belief in Jesus, and this is exclusively God's work:
No one can come to me unless the Father who sent me draws him. (John 6:44)
And when the Gentiles heard this, they began rejoicing and glorifying the word of the Lord, and as many as were appointed to eternal life believed. (Acts 13:48; note, not "as many as believed were appointed to eternal life," as some like to distort it.)
One who heard us was a woman named Lydia.... The Lord opened her heart to pay attention to what was said by Paul. (Acts 16:14)
For it has been granted to you that for the sake of Christ you should not only believe in him but also suffer for his sake. (Phil. 1:29)
So justification is God's work, and so is the sanctification that comes after:
those whom he foreknew he also predestined to be conformed to the image of his Son, in order that he might be the firstborn among many brothers. And those whom he predestined he also called, and those whom he called he also justified. (Rom. 8:29-30).
It is God's work to sanctify those whom he calls to himself: to make them to be like Christ. For this purpose he gives them the Holy Spirit: " God chose you as the firstfruits to be saved, through sanctification by the Spirit and belief in the truth" (2 Thess. 2:13). The Holy Spirit is also a down payment, the token of a promise of our future inheritance, the Kingdom: "In him you also, when you heard the word of truth, the gospel of your salvation, and believed in him, were sealed with the promised Holy Spirit, who is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory" (Eph. 1:13-14). The word translated "guarantee" is a term of commerce, what we today would call a down payment or deposit. It's a promise--in fact, a legally binding contract--to pay the amount in full later.
If God were to justify someone and give him the Holy Spirit to transform him into Christ-likeness, but that person by his own free will could reject God's work in him and return to his lost state, then God is fallible and liable to failure. If God worked justification and sanctification in him, but then denied him his promised inheritance in the Kingdom at the last, he is arbitrary and untrustworthy. Arminians and semi-Pelagians, as well as millennial exclusionists, err.
No, the work of God begins with justification, continues with sanctification, and concludes with glorification: " those whom he justified he also glorified" (Rom. 8:30). What God starts, he finishes, guaranteed.
