No, no contradiction, just differences (2Tim.2:15-'rightly dividing')
There is an organized Church, which is composed of various offices and duties.
In the Organized church, one may have both believers and unbelievers.
The spiritual church is only composed of believers, united by the Holy Spirit after the New Birth (Jn.3), being Justfied by Faith, not works (Eph.2:8, Tit.3:5).
This was the 'mystery' revealed to Paul (Eph.3).
Even the OT assembly could be called a 'church' (Acts.7:38)
Thus, there is two aspects to the 'church'.
An organization that should be only composed of believers in Christ (but sometimes is not) whose goal is to grow in grace (Eph.4), and the spiritual church, the Body of Christ, His Bride, which can only be composed of believers since one can only become part of it through the new birth, being baptized by the Holy Spirit into it.
Thus, even though the various churchs are divided by differing doctrines, if one is saved, there is unity among the individuals, not among the differing churches
I never denied that and the statements you make before this. I am defending the NECESSITY of having a VISIBLE Church so as to be able to even take into consideration Matthew 18. Certainly, Jesus clearly tells us through His parables and teachings that some "inside" the visible Church are not of the Elect. For example, see Mat 7:21.
Thus, even though the various churchs are divided by differing doctrines, if one is saved, there is unity among the individuals, not among the differing churches
There were NO "various" churches divided by doctrines in the Scriptures! What we have now is not what was present in Scriptures. The various communities shared the SAME faith and the SAME loaf. They shared in communion, they were one Body in more than just name. We do not share in communion. That is why we call Protestants "separated brothers". Sure, we are united in many things, but on some essentials, we disagree. We do not all recognize the Lord in the Breaking of the Bread.
With that said, the Church accurately considers that individual Protestants can be united to the Catholic Church - while the entire community is not. There are a lot of unwitting Catholics and a lot of "Catholics" who are not...
Regards