Often some Republican will speak of the party being a big tent where a broad range of views can fit in. What about such a perspective on the Christian faith?

"There is one body, and one Spirit, even as also ye were called in one hope of your calling; one Lord, one faith, one baptism, one God and Father of all, who is over all, and through all, and in all." (Eph 4:4-6, ERV)

"Beloved, while I was giving all diligence to write unto you of our common salvation, I was constrained to write unto you exhorting you to contend earnestly for the faith which was once for all delivered unto the saints." (Jude 1:3, ERV)

"But though we, or an angel from heaven, should preach unto you any gospel other than that which we preached unto you, let him be anathema." (Gal 1:8, ERV)

"What then? only that in every way, whether in pretence or in truth, Christ is proclaimed; and therein I rejoice, yea, and will rejoice." (Phil 1:18, ERV)

"For such men are false apostles, deceitful workers, fashioning themselves into apostles of Christ. And no marvel; for even Satan fashioneth himself into an angel of light. It is no great thing therefore if his ministers also fashion themselves as ministers of righteousness; whose end shall be according to their works." (2Cor 11:13-15, ERV)

What doctrines are surely required to be believed to be within the one Christian faith? Considering there are degrees in error and heresies, at what point does error or heresy put one out of possibility of eternal life?