John 6:44, 10:26, among other verses refute your position.
NOWHERE does the Bible teach "everyone has a capacity to believe Christ".
All that is needed is revelation before a man can believe unless previously hardened
John 6:45 (KJV 1900) — 45 It is written in the prophets, And they shall be all taught of God. Every man therefore that hath heard, and hath learned of the Father, cometh unto me.
Romans 10:17 (KJV 1900) — 17 So then faith cometh by hearing, and hearing by the word of God.
John 20:31 (KJV 1900) — 31 But these are written, that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have life through his name.
1 Corinthians 15:1–11 (KJV 1900) — 1 Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand; 2 By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain. 3 For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; 4 And that he was buried, and that he rose again the third day according to the scriptures: 5 And that he was seen of Cephas, then of the twelve: 6 After that, he was seen of above five hundred brethren at once; of whom the greater part remain unto this present, but some are fallen asleep. 7 After that, he was seen of James; then of all the apostles. 8 And last of all he was seen of me also, as of one born out of due time. 9 For I am the least of the apostles, that am not meet to be called an apostle, because I persecuted the church of God. 10 But by the grace of God I am what I am: and his grace which was bestowed upon me was not in vain; but I laboured more abundantly than they all: yet not I, but the grace of God which was with me. 11 Therefore whether it were I or they, so we preach, and so ye believed.
etc