Answer: No, they do not always agree.
The main doctrines that most Christians agree on are
(a) The deity of Jesus Christ, His virgin birth, and His sinlessness;
(b) The substitutionary atonement of Jesus Christ when e died on the cross;
(c) Salvation by grace apart from works;
(d) The presbytery or the structure of church government.
Doctrines that many Christians disagree on are
(a) The priesthood of believers (Christians);
(b) Speaking in tongues;
(c) Eschatology (doctrines about end times);
(d) God's promised future prosperity for Israel;
(e) The rapture, the order of resurrections, and the millennial reign of Christ on earth.